Semiconductor light emitting device, backlight, color image display device and phosphor to be used for them

ABSTRACT

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image. 
     A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100° C. to the emission intensity at 25° C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.

TECHNICAL FIELD

The present invention relates to a semiconductor light emitting deviceuseful for a color image display device to realize an image with a highcolor purity, and a backlight employing it. Further, the presentinvention relates to a color image display device to realize an imagewith a high color purity to meet with the emission wavelength of animproved backlight, a novel phosphor suitable for such a semiconductorlight emitting device and a process for its production.

BACKGROUND ART

In recent years, liquid crystal display devices are used not only in theconventional application to personal computer monitors but also inapplication to ordinary color televisions. The color reproduction rangeof the color liquid crystal display devices is determined by colors oflight emitted from the red, green and blue pixels and, wherechromaticity points of the respective color pixels in the CIE XYZcolorimetric system are represented by (x_(R),y_(R)), (x_(G),y_(G)) and(x_(B),y_(B)), the color reproduction range is represented by an area ofa triangle defined by these three points on an x-y chromaticity diagram.Namely, the larger the area of this triangle, the more vivid color imagethe display devices reproduce. The area of this triangle is normallyexpressed by a ratio of the area of the triangle to an area of areference triangle formed by three points of the three primary colors,red (0.67,0.33), green (0.21,0.71) and blue (0.14,0.08), in the standardsystem defined by U.S. National Television System Committee (NTSC) (inunit of %, which will be referred to hereinafter as “NTSC ratio”). Theordinary notebook computers have the values of approximately 40 to 50%,the desktop computer monitors the values of 50 to 60%, and the existingliquid crystal TVs the values of approximately 70%.

A color image display device utilizing such a color liquid crystaldisplay device is constituted mainly by light shutters utilizing liquidcrystal, a color filter having red, green and blue pixels, and abacklight for transmissive illumination, and the colors of lightsemitted from the red, green and blue pixels are determined by theemission wavelength of the backlight and the spectroscopic curve of thecolor filter.

In the color liquid crystal display devices, the color filter extractsonly wavelengths in necessary regions from the emission distribution ofthe backlight, to provide the red, green and blue pixels.

Methods for production of this color filter proposed heretofore includesuch methods as dyeing, pigment dispersion, electrodeposition, printing,ink jetting and so on. The colorants for coloring used to be dyes, butare now pigments in view of reliability and durability as liquid crystaldisplay devices. Accordingly, at present, the pigment dispersion is mostcommonly used as a method for production of the color filter from theviewpoint of productivity and performance. In general, when the samecolorants are used, the NTSC ratio and the brightness are in a trade-offrelation, and the colorants are suitably selected for use depending onthe particular application. Namely, if it is attempted to increase theNTSC ratio by adjusting the color filter in order to reproduce a vividcolor image, the screen tends to be dark. Inversely, if the brightnessis increased, the NTSC ratio tends to be low, and it tends to bedifficult to reproduce a vivid image.

On the other hand, as a backlight, it has been common to employ oneusing as a light source a cold-cathode tube with emission wavelengths inthe red, green and blue wavelength regions and using an opticalwaveguide plate for converting light emitted from this cold-cathodetube, to a white surface light source. In recent years, a light emittingdiode (LED) has been used, since it has a longer operating life,requires no inverter, presents high brightness, is mercury free, etc.

Here, in a backlight employing conventional LED, blue light-emitting LEDis used in such a manner that part of light emitted from this LED isconverted to yellow light by a yellow-emitting phosphor, and white lightobtained by color mixing of the blue light and the yellow light is usedas a surface light source by means of an optical waveguide.

However, in the above light source, the yellow emitting phosphor wasused, whereby emission with wavelengths unnecessary from the viewpointof the color purity of red and green was substantial, and it wasdifficult to obtain a display with high color reproducibility (HighGamut). Here, it is possible, at least in principle, to increase thecolor purity of red and green by cutting off light with unnecessarywavelengths by means of a color filter, but as mentioned above, if it isattempted to increase the NTSC ratio by adjusting the color filter inorder to reproduce the vivid color image, the majority of emission ofthe backlight will be cut off, whereby there has been a problem that thebrightness decreases substantially. Especially, by this method, emissionof red decreases substantially, whereby it has been practicallyimpossible to reproduce a strongly reddish color.

In order to overcome this problem, a method of combining red-, green-and blue-emitting LEDs (Non-Patent Document 1) has been proposed, and bythis method, a display having an extremely high color reproducibilityhas been prepared on a trial basis. However, in such a color imagedisplay device, LED chips independent for red, green and blue,respectively, are combined, whereby there have been problems suchthat 1) it takes time and labor to mount them, 2) since the respectiveLED chips for red, green and blue are disposed at finite distances, itis required to take the distance of an optical waveguide to be long tosufficiently mix emitted lights from the respective LED chips, and 3)since the white chromaticity is adjusted by combining the integralmultiple of the respective LED chips, adjustment of the white balancecan not be continuously carried out.

Further, Patent Document 1 discloses a color image display device havingan NTSC ratio of at least 60%, which is constituted by a combination ofa blue or deep blue emitting LED and a phosphor. With this color imagedisplay device, a broad color reproducibility may be attained ascompared with the above mentioned yellow emitting phosphor, but emittedlights with wavelengths which are unnecessary from the viewpoint of thecolor purity of red and green, are substantial, and a still broadercolor reproducibility has been desired.

Further, Patent Documents 2 and 3 disclose semiconductor light emittingdevices having specific phosphors combined, which is useful, forexample, as a light source for backlight for e.g. liquid crystaldisplays. However, in a case where such semiconductor light emittingdevices are practically combined with color filters to constitute colorimage display devices for e.g. liquid crystal displays, there have beencases where the emission of backlight tends to be inadequate, orchromaticity deviation is likely to occur.

On the other hand, WO2004/25359 (Patent Document 4) discloses that animage display device having a high NTSC ratio is obtainable by acombination of a light source for backlight satisfying specificconditions with a color filter. However, with respect to the demand forhigh performance in recent years, the specifically disclosed lightemitting device employing the 3.5MgO.0.5MgF₂.GeO₂:Mn⁴⁺ type, Y₂O₃:Eutype and YVO₄:Eu³⁺ type phosphors, is inadequate from the viewpoint ofthe emission efficiency, etc., and it is desired to develop one havinghigher performance.

Further, in recent years, a light emitting device employing K₂ TiF₆:Mnhas been known as a red emitting phosphor (Patent Documents 5 to 7).However, by a study by the present inventors, it has been found thatsuch a light emitting device undergoes substantial deterioration of theproperties and is not practically durable for a reason assumed to besuch that hydrogen fluoride is generated by the reaction with moisturein air, and it has been desired to develop one having a higherperformance.

Further, with a view to suppressing deterioration of phosphors, it isknown to cover the surface of water-soluble phosphor particles with acoating of e.g. a metal oxide (Patent Document 8), but such a methodrequires a special apparatus and is inadequate from the viewpoint of thetypes of the useful phosphors, etc.

Non-Patent Document 1: Monthly display, April 2003 issue (p 42-46)

Patent Document 1: WO2005/111707

Patent Document 2: JP-A-2002-171000

Patent Document 3: U.S. Pat. No. 6,809,781

Patent Document 4: WO2004/025359

Patent Document 5: U.S. Patent Application Publication No. 2006/0071589

Patent Document 6: U.S. Patent Application Publication No. US2006/0169998

Patent Document 7: U.S. Patent Application Publication No. US2007/0205712

Patent Document 8: JP-A-2005-82788

DISCLOSURE OF THE INVENTION Technical Problem

The present invention has been made in view of the above-describedsituation and has an object to provide a semiconductor light emittingdevice which, particularly when used as a backlight for a color imagedisplay device, is capable of accomplishing broad color reproducibilityas an entire image by adjustment with a color filter, without impairingbrightness of the image, and at the same time, by carrying out the red,green and blue emissions by one chip, is free from impairing theproductivity in its mounting and which further facilitates adjustment ofthe white balance. Further, the present invention has an object toprovide a backlight and color image display device employing such asemiconductor light emitting device. In addition, the present inventionhas an object to provide a narrow band red emitting phosphor which maybe preferably used for such a semiconductor light emitting device and aprocess for its production.

Solution to Problem

As a result of an extensive study, the present inventors have found thatthe cause of the inadequate emission of a backlight for a color imagedisplay device or of the chromaticity deviation, is attributable to thecharacteristics of phosphors and can be solved by improvement of thephosphors. Further, it has been found it possible to closely relate theNTSC ratio and the light use efficiency to represent the performance ofthe entire color image display device. Heretofore, as described above,the NTSC ratio and the light use efficiency were in a trade-offrelation, and in a case where the performance of a color image displaydevice is to be improved, the primary emphasis was placed on eitherimprovement of the NTSC ratio at the sacrifice of the light useefficiency or improvement of the light use efficiency at the sacrificeof NTSC ratio.

The present inventors have found a light emitting device whereby it ispossible to set the light emission efficiency to be higher than ever bycombining a plurality of phosphors having improved emission wavelengthsand light emission (excitation) can be efficiently carried out by alight emitting device having specific emission wavelengths. In addition,they have found it possible to realize a semiconductor light emittingdevice having high durability by adopting a specific construction of thedevice. Further, they have found it possible to realize a semiconductorlight emitting device with higher luminance when specific phosphors areselectively employed among them.

Further, they have found it possible to realize a color image displaydevice which is capable of realizing an image display having high colorpurity i.e. which has a light use efficiency higher than ever even at ahigh NTSC ratio, by using such a semiconductor light emitting device asa backlight and combining such a backlight with a color filter mostsuitable for the emission wavelengths of the backlight.

The present invention has been made on the basis of such discoveries andprovides the following.

1. A semiconductor light emitting device comprising a solid lightemitting device to emit light in a blue or deep blue region or in anultraviolet region and phosphors, in combination, wherein said phosphorscomprise a green emitting phosphor having at least one emission peak ina wavelength region of from 515 to 550 nm and a red emitting phosphorhaving at least one emission peak with a half-value width of at most 10nm in a wavelength region of from 610 to 650 nm, having substantially noexcitation spectrum in the emission wavelength region of said greenemitting phosphor and containing Mn⁴⁺ as an activated element, and saidgreen emitting phosphor and said red emitting phosphor are ones, ofwhich the variation rate of the emission peak intensity at 100° C. tothe emission intensity at 25° C., when the wavelength of the excitationlight is 400 nm or 455 nm, is at most 40%.

2. The semiconductor light emitting device according to the above 1,wherein the green emitting phosphor contains at least one compoundselected from the group consisting of an aluminate phosphor, a sialonphosphor and an oxynitride phosphor.

3. The semiconductor light emitting device according to the above 1,wherein the red emitting phosphor is one, of which the variation rate ofthe emission peak intensity at 100° C. to the emission peak intensity at25° C., when the wavelength of the excitation light is 455 nm, is atmost 18%.

4. The semiconductor light emitting device according to the above 1,wherein the red emitting phosphor has a main emission peak with ahalf-value width of at most 10 nm in a wavelength region of from 610 to650 nm.

5. The semiconductor light emitting device according to the above 1,wherein the red emitting phosphor is a fluoride complex phosphor, andsaid solid light emitting device is formed on an electrically conductivesubstrate.

6. The semiconductor light emitting device according to the above 5,wherein the red emitting phosphor is one, of which the thermallydecomposed fluorine amount per 1 g of the phosphor at 200° C. is atleast 0.01 μg/min.

7. The semiconductor light emitting device according to the above 6,wherein the red emitting phosphor is one, of which the solubility in 100g of water at 20° C. is at least 0.005 g and at most 7 g.

8. The semiconductor light emitting device according to the above 1,wherein the red emitting phosphor is a fluoride complex phosphor, andthe semiconductor light emitting device is provided with a layercontaining said red emitting phosphor and has at least one of thefollowing structures (a) to (c):

(a) a layer of a material not containing said red emitting phosphor ispresent between the solid light emitting device and the layer containingsaid red emitting phosphor,

(b) part or whole of the surface of the light emitting device is coveredby a layer of a material not containing said red emitting phosphor, and

(c) the layer containing said red emitting phosphor is covered by alayer of a material not containing said red emitting phosphor.

9. The semiconductor light emitting device according to the above 8,wherein the red emitting phosphor is one, of which the thermallydecomposed fluorine amount per 1 g of the phosphor at 200° C. is atleast 0.01 μg/min.

10. The semiconductor light emitting device according to the above 9,wherein the red emitting phosphor is one, of which the solubility in 100g of water at 20° C. is at least 0.005 g and at most 7 g.

11. The semiconductor light emitting device according to any one of theabove 1 to 10, wherein the red emitting phosphor contains a crystalphase having a chemical composition represented by any one of thefollowing formulae (1) to (8):

M^(I) ₂[M^(IV) _(1-x)R_(x)F₆]  (1)

M^(I) ₃[M^(III) _(1-x)R_(x)F₆]  (2)

M^(II)[M^(IV) _(1-x)R_(x)F₆]  (3)

M^(I) ₃[M^(IV) _(1-x)R_(x)F₇]  (4)

M^(I) ₂[M^(III) _(1-x)R_(x)F₅]  (5)

Zn₂[M^(III) _(1-x)R_(x)F₇]  (6)

M^(I)[M^(III) _(2-2x)R_(2x)F₇]  (7)

Ba_(0.65)Zr_(0.35)F_(2.70):Mn⁴⁺  (8)

In the formulae (1) to (8), M^(I) is at least one monovalent groupselected from the group consisting of Li, Na, K, Rb, Cs and NH₄, M^(II)is an alkaline earth metal element, M^(III) is at least one metalelement selected from the group consisting of Groups 3 and 13 of thePeriodic Table, M^(IV) is at least one metal element selected from thegroup consisting of Groups 4 and 14 of the Periodic Table, R is anactivated element containing at least Mn, and x is a numerical value of0<x<1.

12. The semiconductor light emitting device according to any one of theabove 1 to 10,

wherein the red emitting phosphor contains a crystal phase having achemical composition represented by the following formula (1′), whereinthe proportion of Mn based on the total mols of M^(IV) and Mn is atleast 0.1 mol % and at most 40 mol %, and the specific surface area isat most 1.3 m²/g:

M^(I′) ₂M^(IV′)F₆:R  (1′)

In the formula (1′), M^(I′) is at least one element selected from thegroup consisting of K and Na, M^(IV′) is at least one metal elementselected from the group consisting of Groups 4 and 14 of the PeriodicTable containing at least Si, and R is an activated element containingat least Mn.

13. A backlight having the semiconductor light emitting device asdefined in any one of the above 1 to 12 as a light source.

14. A color image display device comprising light shutters, a colorfilter having at least trichromatic color elements of red, green andblue corresponding to the light shutters and the backlight as defined inthe above 13, in combination, wherein the relationship between the lightuse efficiency Y and the NTSC ratio W representing the colorreproduction range of the color image display device is represented bythe following formula:

$\begin{matrix}{Y \geqq {{{- 0.4}W} + {64\mspace{14mu} {W( {{{where}\mspace{14mu} W} \geqq 85} )}}}} & \; \\{X = \frac{\int_{380}^{780}{{\overset{\_}{x}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & {x = \frac{X}{X + Y + Z}} \\{Y = \frac{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & {y = \frac{Y}{X + Y + Z}} \\{Z = \frac{\int_{380}^{780}{{\overset{\_}{z}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & \;\end{matrix}$

wherein the definitions of the respective symbols are as follows:

x(λ), y(λ), z(λ): color matching functions of XYZ colorimetric system

S(λ): relative emission spectrum of the backlight

T(λ): transmittance of the color filter

15. The color image display device according to the above 14, whereinthe green pixel of the color filter contains a zinc phthalocyaninebromide pigment.

16. The color image display device according to the above 14 or 15,wherein each pixel of the color filter has a film thickness of at least0.5 μm and at most 3.5 μm.

17. A phosphor containing a crystal phase having a chemical compositionrepresented by the following formula (1′), wherein the proportion of Mnbased on the total mols of M^(IV′) and Mn is at least 0.1 mol % and atmost 40 mol %, and the specific surface area is at most 1.3 m²/g:

M^(I′) ₂M^(IV′)F₆:R  (1′)

In the formula (1′), M^(I′) is at least one element selected from thegroup consisting of K and Na, M^(IV′) is at least one metal elementselected from the group consisting of Groups 4 and 14 of the PeriodicTable containing at least Si, and R is an activated element containingat least Mn.

18. The phosphor according to the above 17, wherein the particle sizedistribution of said red emitting phosphor has one peak value.

19. The phosphor according to the above 17 or 18, wherein the quantiledeviation of the particle size distribution is at most 0.6.

20. A process for producing the phosphor as defined in any one of theabove 17 to 19, which has a step of reacting a solution containing atleast Si and F with a solution containing at least K, Mn and F to obtaina compound represented by the above formula (1′).

21. A process for producing a phosphor containing a crystal phase havinga chemical composition represented by the following formula (1′), whichhas a step of mixing at least two types of solutions each containing atleast one element selected from the group consisting of K, Na, Si, Mnand F:

M^(I′) ₂M^(IV′)F₆:R  (1′)

In the formula (1′), M^(I′) is at least one element selected from thegroup consisting of K and Na, M^(IV′) is at least one metal elementselected from the group consisting of Groups 4 and 14 of the PeriodicTable containing at least Si, and R is an activated element containingat least Mn.

22. A phosphor-containing composition comprising the phosphor as definedin any one of the above 17 to 19 and a liquid medium.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to obtain a lightemitting device capable of accomplishing broad color reproducibility bya light emitting device comprising a light emitting device to emit lightwith a specific wavelength and phosphors having specific characteristicsin combination, and it is further possible to obtain a light emittingdevice which is excellent in luminance and emission efficiency and hashigh durability. Further, by using such a light emitting device as alight source and properly prescribing the relation between the NTSCratio and the light use efficiency, it is possible to realizereproduction of deep red and green without impairing brightness of theimage thereby to accomplish broad color reproducibility as the entireimage. Further, red, green and blue emissions can be carried out by onechip, whereby it is possible to provide a color image display devicewithout impairing the productivity in its mounting and wherebyadjustment of the white balance is easy.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1, FIG. 1( a) is a cross sectional view of a verticalsemiconductor light emitting device, and FIG. 1( b) is a cross sectionalview of a horizontal semiconductor light emitting device.

FIG. 2 is a cross sectional view of a light emitting device according tothe first embodiment (vertical construction) of the present invention.

FIG. 3 is a schematic perspective view showing an embodiment of thelight emitting device of the present invention.

In FIG. 4, FIG. 4( a) is a schematic cross sectional view showing anembodiment of a shell type light emitting device of the presentinvention, and FIG. 4( b) is a schematic cross sectional view showing anembodiment of a surface mounting light emitting device of the presentinvention.

FIG. 5 is a schematic cross sectional view showing an embodiment of anilluminating device of the present invention.

FIG. 6 is a view showing a construction of a color liquid crystaldisplay device of a TFT type.

FIG. 7 is a graph showing the relation between the NTSC ratio and thelight use efficiency of a color image display device according to thepresent invention.

FIG. 8 is a cross sectional view showing an example of a backlightdevice suitable for the present invention.

FIG. 9 is a cross sectional view showing another example of a backlightdevice suitable for the present invention.

FIG. 10 is a transmittance spectrum of a color filter for Example I-1,3, 5 or 7.

FIG. 11 is a transmittance spectrum of a color filter for Example I-2,4, 6, 8 to 10 and Comparative Example I-3 or 4.

FIG. 12 is charts showing X-ray powder diffraction patterns of phosphorsobtained in Examples II-1-1 and II-1-2 and Comparative Example II-1-1.

FIG. 13 is a chart showing an excitation/emission spectrum of a phosphorobtained in Example II-1-1.

FIG. 14A is charts showing the particle size distribution curves ofphosphors obtained in Examples II-1-1(a) and II-1-2(b) and II-1-9(c).

FIG. 14B is a chart showing the particle size distribution curve of aphosphor obtained in Comparative Example II-1-1.

FIG. 15A is SEM photographs of phosphors obtained in Examples II-1-1(a),II-1-2(b) and II-1-9(c).

FIG. 15B is a SEM photograph of a phosphor obtained in ComparativeExample II-1-1.

FIG. 16 is a chart showing an emission spectrum of a semiconductor lightemitting device prepared in Example II-2-1.

FIG. 17 is a chart showing an emission spectrum of a semiconductor lightemitting device prepared in Comparative Example II-2-1.

FIG. 18 is a chart showing an emission spectrum of a semiconductor lightemitting device prepared in Example II-2-2.

FIG. 19 is a chart showing an emission spectrum of a semiconductor lightemitting device prepared in Example II-2-3.

FIG. 20 is a chart showing an emission spectrum of a semiconductor lightemitting device prepared in Comparative Example II-2-2.

FIG. 21 is a chart showing an emission spectrum of a semiconductor lightemitting device prepared in Comparative Example II-2-3.

FIG. 22 is a view showing an embodiment of a preferred layerconstruction in a light emitting device of the present invention.

FIG. 23 is views showing embodiments (a), (b) and (c) of preferred layerconstructions in a light emitting device of the present invention.

FIG. 24 is a view showing an embodiment of a preferred layerconstruction in a light emitting device of the present invention.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1: Phosphor-containing portion (second emitter)    -   2: Excitation light source (first emitter) (LD)    -   3: Substrate    -   4: Light emitting device    -   5: Mount lead    -   6: Inner lead    -   7: Excitation light source (first emitter)    -   8: Phosphor-containing portion    -   9: Electrically conductive wire    -   10: Mold component    -   11: Surface-emitting illuminating device    -   12: Holding case    -   13: Light emitting device    -   14: Diffusion plate    -   15: Frame    -   16: Electrically conductive wire    -   17: Electrode    -   18: Electrode    -   20: Semiconductor light emitting device    -   21: Substrate    -   22: Buffer layer    -   23: Contact layer    -   24: First electroconductive clad layer    -   25: Active layer structure    -   26: Second electroconductive clad layer    -   27: Second electroconductive lateral electrode    -   28: First electroconductive lateral electrode    -   29: Second current injection region    -   31: Light source    -   32: Optical waveguide    -   33: Light diffusion sheet    -   34, 40: Polarizer    -   35, 38: Glass substrate    -   36: TFT    -   37: Liquid crystal    -   39: Color filter    -   41: Light guide    -   41 a: One side edge surface of light guide    -   41 b: One plate surface of light guide (light emitting surface)    -   41 c: Plate surface of light guide opposite to the light        emitting surface    -   42: Array    -   43: Light control sheet    -   44, 44′: Light extracting mechanism    -   44 a: Dots    -   44 b: Roughened surface pattern    -   45: Reflecting sheet    -   101: p-type electrode    -   102: n-type electrode    -   103: p-type layer    -   104: n-type layer    -   105: Electrically conductive substrate    -   106: Insulating substrate    -   110: Semiconductor light emitting device A    -   111: Material layer B (fluoride complex phosphor-containing        layer)    -   112: Material layer C    -   113: Material layer D    -   114: Material layer E

DESCRIPTION OF EMBODIMENTS

Now, the present invention will be described in detail with reference toits embodiments, but it should be understood that the present inventionis by no means restricted to such embodiments and may be practiced invarious modifications within its scope.

In the present invention, “a color image display device” means an entireconstruction including not only light shutters, a color filter and abacklight but also their driving circuits, control circuits, etc., whichis capable of displaying a color image in a state controlled inaccordance with input signals.

Further, “a color image display element” means a construction to emitlight from the backlight through the light shutters and color filter,having a construction to control the driving of the optical shutters andbacklight excluded from the “color image display device”.

Further, in the present specification, a numerical value rangerepresented by “to” means a range containing the numerical values givenbefore and after “to” as the lower limit value and the upper limitvalue.

Further, with respect to compositional formulae of phosphors in thisspecification, adjacent compositional formulae are delimited by a comma“,”. Further, a plurality of elements being delimited by commas “,”means that one or more of such comma-delimited elements may be containedin an optional combination or composition. For example, a compositionalformula of “(Ca,Sr,Ba)Al₂O₄:Eu” comprehensively represents all of“CaAl₂O₄:Eu”, “SrAl₂O₄:Eu”, “BaAl₂O₄: Eu”, “Ca_(1-x)Sr_(x)Al₂O₄:Eu”,“Sr_(1-x)Ba_(x)Al₂O₄:Eu”, “Ca_(1-x)Ba_(x)Al₂O₄:Eu” and“Ca_(1-x-y)Sr_(x)Ba_(y)Al₂O₄:Eu” (provided that in the above formulae,0<x<1, 0<y<1, and 0<x+y<1).

1. Solid Light Emitting Device

The emission wavelength of the solid light emitting device is notparticularly limited so long as it overlaps with absorption wavelengthsof the phosphors, and it is possible to use illuminants in a wideemission wavelength range, but its emission wavelength is usuallypreferably at least 200 nm. In a case where blue light is used asexcitation light, it is preferred to use an illuminant having anemission peak wavelength of usually at least 420 nm, preferably at least430 nm, more preferably at least 440 nm, further preferably at least 450nm and usually at most 490 nm, preferably at most 480 nm, morepreferably at most 470 nm, further preferably at most 460 nm. On theother hand, in a case where deep blue light (hereinafter sometimesreferred to as near ultraviolet light) or ultraviolet light is used asexcitation light, it is preferred to use an illuminant having anemission peak wavelength of usually at most 420 nm, preferably at most410 nm, more preferably at most 400 nm. A red emitting phosphorpreferably used in the present invention, is excited usually by bluelight. Accordingly, in a case where near ultraviolet light orultraviolet light is used, the red emitting phosphor is usually excited(indirectly excited) by blue light emitted from a blue-emitting phosphorexcited by such light, and it is preferred to select excitation lighthaving a wavelength to match the excitation band and the blue-emittingphosphor.

The solid light emitting device may, for example, be an organicelectroluminescence light emitting device, an inorganicelectroluminescence light emitting device or a semiconductor lightemitting device. However, a semiconductor light emitting device ispreferably employed, and for example, preferred is an InGaN type, GaAlNtype, InGaAlN type or ZnSeS type semiconductor light emitting devicecrystal-grown by e.g. a MOCVD method on a substrate of e.g. siliconcarbide, sapphire or gallium nitride. In order to obtain a high outputpower, the light source size may be enlarged, or the number of lightsources may be increased. Further, it may be an edge face emission typeor surface emission type laser diode. A blue or deep blue-emitting LEDis preferably employed, since it has a wavelength capable of efficientlyexciting phosphors, and it is accordingly possible to obtain a lightsource having a large light quantity.

Among them, as a first illuminant, a GaN type LED or LD (laser diode)using a GaN type compound semiconductor, is preferred, because ascompared with a SiC type LED or the like which emits light in thisregion, the GaN type LED or LD has a remarkably large emission outputpower or external quantum efficiency, and by combining it with the abovephosphors, it is possible to obtain a very bright emission with a lowelectric power. For example, to a current load of 20 mA, the GaN typeLED or LD usually has an emission intensity of at least 100 times ascompared with a SiC type. The GaN type LED or LD is preferably onehaving an Al_(X) Ga_(Y) N emission layer, a GaN emission layer or anIn_(x) Ga_(Y) N emission layer. Among them, as the GaN type LED, onehaving an In_(x) Ga_(Y) N emission layer is particularly preferred,since the emission intensity is very high, and one having a multiplequantum well structure comprising an In_(x) Ga_(Y) N layer and a GaNlayer, is further preferred.

In the above, “x+y” is usually a value within a range of from 0.8 to1.2. In the GaN type LED, one having Zn or Si doped on such an emissionlayer or one having no dopant is preferred in order to adjust theemission characteristics.

The GaN type LED is one comprising such an emission layer, a p-layer, an-layer, electrodes and a substrate, as fundamental constitutingelements. One having a hetero structure wherein the emission layer issandwiched by n-type and p-type Al_(X) Ga_(Y) N layers, GaN layers orIn_(x) Ga_(Y) N layers, is preferred, since the emission efficiency ishigh. More preferred is one wherein the hetero structure is in the formof a multiple quantum well structure, since the emission efficiency ishigher.

As the first phosphor, one phosphor may be used alone or two or morephosphors may be used in optional combination and ratio.

LED chips as the above-mentioned semiconductor light emitting devicesinclude one having a vertical device structure and one having ahorizontal device structure as shown in FIGS. 1( a) and 1(b). In a casewhere a LED chip having a vertical device structure, formed on anelectrically conductive substrate, is used, it is preferred to employ afluoride complex phosphor as the red emitting phosphor with a view toimprovement of the durability of the light emitting device, specificallyfrom such a viewpoint that deterioration with time of the light emittingdevice at a temperature of 85° C. under a humidity of 85% can besuppressed.

Here, the vertical type device structure is a structure of a so-calledvertically conductive (vertical) light emitting device, wherein adesired light emitting device structure is expitaxially grown on anelectrically conductive substrate, and one electrode is formed on thesubstrate and the other electrode is further formed on the expitaxiallygrown layer, so that a current is conducted in the expitaxial growthdirection.

Preparation of a semiconductor light emitting device by using a p-njunction type element will be described with reference to the drawings.FIG. 1( a) shows a vertical device structure and its currentdistribution, and FIG. 1( b) shows a horizontal device structure and itscurrent distribution.

The vertical device structure shown in FIG. 1( a) is a structure whereina n-type layer (104) and a p-type layer (103) are deposited on anelectrically conductive substrate (105), and a p-type electrode (101) isformed on the p-type layer (103) and a n-type electrode (102) is formedon the electrically conductive substrate (105). In this case, when thedirection perpendicular to the interface between the respective layersis taken as a longitudinal direction, the current flows only in thelongitudinal direction in the electrically conductive substrate (105),n-type layer (104) and p-type layer (103).

The horizontal device structure shown in FIG. 1( b) is a structureadopted in a case where a device is formed on an insulating substratemade of e.g. sapphire. It is a structure wherein a n-type layer (104)and a p-type layer (103) are deposited on an insulating substrate (106),a p-type electrode (101) is formed on the p-type layer (103), and an-type electrode (102) is formed on the n-type layer (104) exposed bye.g. dry etching. In this case, when the direction horizontal to theinterfaces between the respective layers is taken as a horizontaldirection, the current flows in the horizontal direction in the n-typelayer (104), whereby the device resistance increases, and the electricfield tends to be concentrated on the n-type electrode (102) side, andthe current distribution tends to be non-uniform.

Now, a typical example of the vertical device structure will bedescribed.

As shown in FIG. 2, a semiconductor light emitting device (20) accordingto the embodiment of the present invention has a substrate (21) and acompound semiconductor thin film crystal layer (hereinafter sometimesreferred to simply as a thin film crystal layer) deposited on one sideof the substrate (21). The thin film crystal layer is constituted by,for example, a first electroconductive semiconductor layer comprising abuffer layer (22) and a first electroconductive clad layer (24), asecond electroconductive semiconductor layer comprising an active layerstructure (25) and a second electroconductive clad layer (26), and acontact layer (23), deposited in this order from the substrate (21)side.

On a portion of the surface of the contact layer (23), a secondelectroconductive lateral electrode (27) for current injection isdisposed, and the portion where the contact layer (23) and the secondelectroconductive lateral electrode (27) are in contact, constitutes asecond current injection region (29) to inject a current to the secondelectroconductive semiconductor layer.

Further, a first electroconductive lateral electrode (28) is disposed onthe rear side i.e. the side of the substrate (21) opposite to the thinfilm crystal layer.

By the disposition of the second electroconductive lateral electrode(27) and the first electroconductive lateral electrode (28) as describedabove, the two are disposed on the opposite sides with the substrate(21) interposed, and the semiconductor light emitting device (20) isconstituted as a so-called vertical semiconductor light emitting device.

As the substrate (21), an electrically conductive substrate or onehaving an electrically conductive material packed through a part of aninsulating substrate, may be used. In a case where an electricallyconductive substrate is to be used, a GaN substrate or a ZnO substratemay, for example, be mentioned in addition to a SiC substrate. A SiCsubstrate and a GaN substrate are particularly preferred, since theelectrical resistance can be suppressed to be low, and the electricalconductivity can be made high.

The reason as to why a vertical device structure is preferred for asemiconductor light emitting device to be used for a light emittingdevice containing a Mn⁴⁺-activated fluoride complex phosphor, is notclearly understood. However, it has been observed that as compared witha horizontal device structure, a color change of the electrode surfaceof a LED chip having a vertical device structure is less by microscopicobservation of the electrode surface after the durability test.

It is considered when applying current to a semiconductor light emittingdevice, a corrosive substance (containing F) will be formed from theMn⁴⁺-activated fluoride complex phosphor and will damage a wire, wherebythe damaged wire will have a large resistance. As compared with ahorizontal device structure, a semiconductor light emitting devicehaving a vertical device structure has only one electrode on the upperside, whereby it is considered that the damage to the wire or electrodeis little, and the change in the electrical conductivity is little, suchbeing desirable.

Further, it is considered that the corrosive substance to be formed fromthe Mn⁴⁺-activated fluoride complex phosphor when applying current, maycontain an ion conductive substance. With one having a horizontal devicestructure, the possibility tends to be high such that leak current flowsbetween the electrodes since the distance between the two electrodes isshort. Whereas, with the semiconductor light emitting device having avertical device structure, the distance between the two electrodes islong, and such a possibility is considered to be low.

2. Phosphors

The light emitting device of the present invention is provided withphosphors which are directly or indirectly excited by light emitted fromthe above-described solid light emitting device, thereby to emit lights.The phosphors are characterized in that they comprise a green emittingphosphor and a red emitting phosphor having the followingcharacteristics.

(2-1) Temperature Dependency of the Emission Peak Intensity

The green emitting phosphor and the red emitting phosphor to be used inthe present invention are ones, of which the variation rate of theemission peak intensity at 100° C. to the emission peak intensity at 25°C., when the wavelength of the excitation light is 400 nm or 455 nm, isat most 40%, preferably at most 30%, more preferably at most 25%,further preferably at most 22%, still further preferably at most 18%,particularly preferably at most 15%.

The light emitted from the solid light emitting device is absorbed bythe phosphors and the binder which maintains the phosphors. The binderis thereby heated to heat the phosphors. Further, the phosphorsthemselves are heated by absorption of the light emitted from the solidlight emitting device. Further, at the time of applying current to thesolid light emitting device for emission, the light emitting device isheated by the electrical resistance in the interior of the solid lightemitting device, and as the temperature rises, the phosphors are heatedby heat conduction. By such heating effects, the temperature of thephosphors will reach a level of 100° C. The emission peak intensity ofthe phosphors depends on the temperature, and as the temperature of thephosphors becomes high, the emission peak intensity tends to decrease.Accordingly, in order to ensure that even in a state where light iscontinuously emitted from the solid light emitting device, the colortone will not change as a whole, it is important to ensure that evenwhere the emission peak intensities of the respective phosphors arechanged by an increase of the temperature, the balance will notsubstantially collapse.

In the present invention, the green emitting phosphor and the redemitting phosphor are adjusted by e.g. the compositions so that when thewavelength of the excitation light is 400 nm or 455 nm, the variationrate of the emission peak intensity at 100° C. to the emission peakintensity at 25° C. is within the above-mentioned range. Thus, even ifthe emission peak intensities of the respective phosphors are changed byan increase of the temperature of the respective phosphors, such changeswill be relatively small among the respective phosphors, and the colorof light emitted from the emitting device is not substantially changedas a whole.

Here, the temperature dependency of phosphors may specifically bemeasured, for example, as follows.

Example for Measurement of Temperature Dependency

The measurement of the temperature dependency is carried out by thefollowing procedure by using, for example, MCPD7000 multichannelspectrum measuring apparatus manufactured by Otsuka Electrics Co., Ltd.as an emission spectrum measuring apparatus, for example, ColorLuminance Meter BM5A as a luminance measuring apparatus, and anapparatus having a stage provided with a cooling mechanism by a Peltierelement and a heating mechanism by a heater, and a 150 W xenon lamp as alight source.

A cell containing a sample of a phosphor is placed on the stage, thetemperature is changed at 25° C. and at 100° C. whereby the surfacetemperature of the phosphor is confirmed, and then the phosphors areexcited by light having a wavelength of 400 nm or 455 nmspectroscopically taken out by a diffraction grating from a lightsource, whereby the luminance value and the emission spectrum aremeasured. From the measured emission spectrum, the emission peakintensity is determined. Here, as the measured value of the surfacetemperature of the phosphor on the side irradiated with the excitationlight, a value corrected by using the temperature values measured by aradiation thermometer and a thermocouple, is used.

(2-2) Types of Phosphors

Now, the red emitting phosphor and the green emitting phosphor suitablyused in the present invention will be described in detail.

(2-2-1) Red-Emitting Phosphor

The red emitting phosphor to be combined with the solid light emittingdevice in the semiconductor light emitting device of the presentinvention is a phosphor which has, in addition to the temperaturedependency of the emission peak intensity as described above, at leastone emission peak with a half-value width of at most 10 nm in awavelength region of from 610 to 650 nm, has substantially no excitationspectrum in the emission wavelength region of the after-described greenemitting phosphor and contains Mn⁴⁺ as an activated element.

As it has an emission peak in the above-mentioned wavelength region, thecolor purity of red increases, whereby a high NTSC ratio can berealized.

Especially, the red emitting phosphor to be used in the presentinvention is preferably one having the main emission peak with ahalf-value width of at most 10 nm in a wavelength region of from 610 to650 nm, and the half-value width is preferably at most 8 nm, morepreferably at most 7 nm.

Further, the red emitting phosphor to be used in the present inventionis characterized in that it is not substantially excited in the emissionwavelength region of the after-mentioned green emitting phosphor.Accordingly, the emission of the green emitting phosphor will not beused for the emission of the red emitting phosphor, whereby the emissionof the green emitting phosphor can be utilized efficiently, and theamount of the green emitting phosphor can be reduced. Further, the heatgeneration is thereby reduced, and it is possible to suppress thevariation rate of the emission peak intensity by the temperature of thephosphor, and besides, it is also possible to suppress deterioration ofthe material at the mold portion molded by the after-mentioned curablematerial or therearound. Here, “substantially not excited” means thatthe wavelength corresponding to 1/10 of the maximum excitation intensityof the excitation spectrum of the red emitting phosphor is usually atmost 535 nm, preferably at most 530 nm, more preferably at most 520 nm,further preferably at most 515 nm, although such may depends also on thetype of the green emitting phosphor to be combined. For example, in acase where the after-mentioned BSON is used as the green emittingphosphor, it is preferred to use a red emitting phosphor having awavelength corresponding to 1/10 of the maximum excitation intensity ofthe excitation spectrum in a range of at most 520 nm.

The red emitting phosphor having such characteristics may preferably bea phosphor containing at least one element selected from the groupconsisting of alkali metal elements, alkaline earth metal elements andZn, at least one element selected from the group consisting of Si, Ti,Zr, Hf, Sn, Al, Ga and In, and at least one member selected from halogenelements.

More preferably, phosphors represented by the following formulae (1) to(8) may be mentioned.

M^(I) ₂[M^(IV) _(1-x)R_(x)F₆]  (1)

M^(I) ₃[M^(III) _(1-x)R_(x)F₆]  (2)

M^(I)[M^(IV) _(1-x)R_(x)F₆]  (3)

M^(I) ₃[M^(IV) _(1-x)R_(x)F₇]  (4)

M^(I) ₂[M^(III) _(1-x)R_(x)F₅]  (5)

Zn₂[M^(III) _(1-x)R_(x)F₇]  (6)

M^(I)[M^(III) _(2-2x)R_(2x)F₇]  (7)

Ba_(0.65)Zr_(0.35)F_(2.70):Mn⁴⁺  (8)

In the formulae (1) to (8), M^(I) is at least one monovalent groupselected from the group consisting of Li, Na, K, Rb, Cs and NH₄, M^(II)is an alkaline earth metal element, M^(III) is at least one metalelement selected from the group consisting of Groups 3 and 13 of thePeriodic Table (hereinafter mention of the Periodic Table may sometimesbe omitted), M^(IV) is at least one metal element selected from thegroup consisting of Groups 4 and 14, R is an activated elementcontaining at least Mn, and x is a numerical value of 0<x<1.

M^(I) particularly preferably contains at least one element selectedfrom the group consisting of K and Na.

M^(II) preferably contains at least Ba and particularly preferably isBa.

A preferred specific example of M^(II) may be at least one metal elementselected from the group consisting of Al, Ga, In, Y and Sc. Among them,at least one metal element selected from the group consisting of Al, Gaand In is preferred. Further, it more preferably contains at least Aland particularly preferably is Al.

A preferred specific example of M^(IV) may be at least one metal elementselected from the group consisting of Si, Ge, Sn, Ti and Zr. Among them,Si, Ge, Ti or Zr is preferred. Further, it preferably contains at leastSi and particularly preferably is Si.

x is preferably at least 0.004, more preferably at least 0.010,particularly preferably at least 0.020, and preferably at most 0.30,more preferably at most 0.25, further preferably at most 0.08,particularly preferably at most 0.06.

Preferred specific examples of the compounds represented by the aboveformulae (I) to (8) may be K₂[AlF₅]:Mn⁴⁺, K₃[AlF₆]:Mn⁴⁺, K₃ [GaF₆]:Mn⁴⁺,Zn₂[AlF₇]:Mn⁴⁺, K[In₂F₇]:Mn⁴⁺, K₂[SiF₆]:Mn⁴⁺, Na₂[SiF₆]:Mn⁴⁺,K₂[TiF₆]:Mn⁴⁺, K₃[ZrF₇]:Mn⁴⁺, Ba[TiF₆]:Mn⁴⁺, K₂[SnF₆]:Mn⁴⁺,Na₂[TiF₆]:Mn⁴⁺, Na₂[ZrF₅]:Mn⁴⁺, KRb[TiF₆]:Mn⁴⁺ andK₂[Si_(0.5)Ge_(0.5)F₆]:Mn⁴⁺.

Among the above, it is preferred from the viewpoint of the luminance ofthe light emitting device to use one which contains a crystal phasehaving a chemical composition represented by the following formula (1′),wherein the proportion of Mn based on the total mols of M^(IV′) and Mnis at least 0.1 mol % and at most 40 mol %, and the specific surfacearea is at most 1.3 m²/g:

M^(I′) ₂M^(IV′)F₆:R  (1′)

In the formula (1′), M^(I′) is at least one element selected from thegroup consisting of K and Na, M^(IV′) is at least one metal elementselected from the group consisting of Groups 4 and 14 of the PeriodicTable containing at least Si, and R is an activated element containingat least Mn.

(2-2-2) Red-Emitting Phosphor Represented by M^(I)′₂M^(IV)′F₆:R

A particularly preferred phosphor among the above is a novel compound,which will be described in detail as follows.

(2-2-2-1) Composition of Phosphor

The phosphor of the present invention is a phosphor which contains acrystal phase having a chemical composition represented by the followingformula (1′), wherein the proportion of Mn based on the total mols ofM^(IV′) and Mn is at least 0.1 mol and at most 40 mols, and the specificsurface area is at most 1.3 m²/g:

M^(I′) ₂M^(IV′)F₆:R  (1′)

In the formula (1′), is at least one element selected from the groupconsisting of K and Na, M^(IV′) is at least one metal element selectedfrom the group consisting of Groups 4 and 14 of the Periodic Tablecontaining at least Si, and R is an activated element containing atleast Mn.

In the above formula (1′), M^(I′) contains at least one element selectedfrom the group consisting of K and Na. It may contain either one ofthese elements alone or it may contain both of them in an optionalratio. Further, in addition to the above, it may partially contain analkali metal element such as Li, Rb or Cs, or (NH₄), so long as noinfluence is given to the performance. The content of Li, Rb, Cs or(NH₄) is usually at most 10 mol % usually based on the total M^(I′)amount.

Especially, M^(I′) preferably contains at least K. Usually, based on theentire amount of M^(I′), K is at least 90 mol %, preferably at least 97mol %, more preferably at least 98 mol %, further preferably at least 99mol %. It is particularly preferred to use only K.

In the above formula (1′), M^(IV)′ contains at least Si. Usually, basedon the total amount of M^(IV)′, Si is at least 90 mol %, preferably atleast 97 mol %, more preferably at least 98 mol %, further preferably atleast 99 mol %. It is particularly preferred to use only Si. That is, itparticularly preferably contains a crystal phase having a chemicalcomposition represented by the following formula (1″):

M^(I)′₂SiF₆:R  (1″)

In the above formula (1″), M^(I)′ and R are as defined in the aboveformula (1′).

R is an activated element containing at least Mn, and one or moreselected from the group consisting of Cr, Fe, Co, Ni, Cu, Ru and Ag maybe mentioned as the activated element which may be contained as R otherthan Mn.

R preferably contains Mn usually at least 90 mol %, more preferably atleast 95 mol %, particularly preferably at least 98 mol %, based on thetotal amount of R, and it is particularly preferred that R contains onlyMn.

The phosphor of the present invention is characterized in that theproportion of Mn based on the total mols of M^(IV)′ and Mn (in thepresent invention, this proportion will hereinafter be referred to as“Mn concentration”) is at least 0.1 mol % and at most 40 mol %. If sucha Mn concentration is too low, the absorption efficiency of excitationlight by the phosphor becomes small, whereby the luminance tends todecrease, and if it is too high, the internal quantum efficiency andluminance tend to decrease due to concentration quenching, although theabsorption efficiency becomes high. The Mn concentration is morepreferably at least 0.4 mol %, further preferably at least 1 mol %,particularly preferably at least 2 mol % and at most 30 mol %,preferably at most 25 mol %, further preferably at most 8 mol %,particularly preferably at most 6 mol %.

The phosphor of the present invention is preferably produced by a methoddisclosed in the after-mentioned process for producing a phosphor.However, in the process for producing the phosphor, there will be acertain difference between the charged composition of the raw materialof the phosphor and the composition of the phosphor thereby obtained.The phosphor of the present invention is characterized in that itcontains the above-mentioned specific composition as the composition ofthe obtained phosphor i.e. not the charged composition of the rawmaterials at the time of the production of the phosphor.

Here, the ionic radius (0.53 Å) of Mn⁴⁺ is larger than the ionic radius(0.4 Å) of Si⁴⁺, and Mn⁴⁺ will not be totally solid-solubilized butpartially solid-solubilized in K₂SiF₆, whereby in the phosphor of thepresent invention, as compared with the charged composition, the Mn⁴⁺concentration substantially activated is limited and becomes small.However, for example, by slowly dropwise adding a poor solvent in theafter-described poor solvent precipitation method, even if theconcentration of Mn⁴⁺ contained in the phosphor becomes low, theparticle growth is promoted by the production process of the presentinvention, whereby it is possible to provide a sufficient absorptionefficiency and luminance.

The chemical analysis of the concentration of Mn contained in thephosphor in the present invention can be made, for example, by SEM-EDX.This method is one wherein in a scanning electron microscopic (SEM)measurement, the phosphor is irradiated with an electron beam (e.g.accelerating voltage: 20 kV), whereby characteristic X-rays emitted fromvarious elements contained in the phosphor are detected to carry out anelemental analysis. As apparatus for measurement, for example, SEM(S-3400N) manufactured by Hitachi, Ltd. and energy dispersion X-rayanalyzer (EDX) (EX-250x-act) manufactured by HORIBA, Ltd. may be usedfor the analysis.

Further, the above phosphor may contain, in addition to theabove-described elements constituting the phosphor, one or more elementsselected from the group consisting of Al, Ga, B, In, Nb, Mo, Zn, Ta, W,R_(e) and Mg within a range not to adversely affect the performance ofthe phosphor.

(2-2-2-2) Characteristics of Phosphor <Emission Spectrum>

The phosphor of the present invention preferably has the followingcharacteristics when its emission spectrum is measured under excitationwith light having a peak wavelength of 455 nm.

It is preferred that the peak wavelength λp (nm) in the above emissionspectrum is usually longer than 600 nm, preferably at least 605 nm, morepreferably at least 610 nm and usually at most 660 nm, preferably atmost 650 nm. If such an emission peak wavelength λp is too short, theemission tends to be yellowish, and on the other hand, if it is toolong, the emission tends to be dark reddish. Either case is notdesirable, since the characteristics as orange or red light are likelyto be deteriorated.

Further, with the phosphor of the present invention, it is preferredthat the half-value width of the emission peak (full width at halfmaximum, hereinafter sometimes abbreviated as “FWHM”) in the aboveemission spectrum is usually larger than 1 nm, preferably at least 2 nm,more preferably at least 3 nm and usually less than 50 nm, preferably atmost 30 nm, more preferably at most 10 nm, further preferably at most 8nm, still further preferably at most 7 nm. If this half-value width(FWHM) is too narrow, the emission peak intensity may sometimesdecrease, and if it is too wide, the color purity may sometimesdecrease.

In order to excite the above phosphor with light having a peakwavelength of 455 nm, a xenon light source may, for example, be used.Further, the measurement of the emission spectrum of the phosphor of thepresent invention can be carried out by using, for example, afluorometer (manufactured by JASCO Corporation) equipped with a 150 Wxenon lamp as an excitation light source and a multichannel CCD detectorC7041 (manufactured by Hamamatsu Photonics K.K.) as a spectrum-measuringapparatus. The emission peak wavelength and the half-value width of theemission peak can be calculated from the obtained emission spectrum.

<Quantum Efficiency/Absorption Efficiency>

With the phosphor of the present invention, the higher the internalquantum efficiency, the better. The value of the internal quantumefficiency is usually at least 50%, preferably at least 75%, morepreferably at least 85%, particularly preferably at least 90%. If theinternal quantum efficiency is low, the emission efficiency tends todecrease, such being undesirable.

With the phosphor of the present invention, the higher the externalquantum efficiency, the better. The value of the external quantumefficiency is usually at least 20%, preferably at least 25%, morepreferably at least 30%, particularly preferably at least 35%. If theexternal quantum efficiency is low, the emission efficiency tends todecrease, such being undesirable.

With the phosphor of the present invention, the higher the absorptionefficiency, the better. The value of the absorption efficiency isusually 25%, preferably at least 30%, more preferably at least 42%,particularly preferably at least 50%. If the absorption efficiency islow, the emission efficiency tends to decrease, such being undesirable.

The above internal quantum efficiency, external quantum efficiency andabsorption efficiency can be measured by the methods disclosed inExamples given hereinafter.

<Weight-Average Median Diameter D₅₀>

With the phosphor of the present invention, it is preferred that theweight-average median diameter D₅₀ is usually at least 3 μm, preferablyat least 10 μm and usually at most 50 μm, preferably at most 30 μm. Ifthe weight-average median diameter D₅₀ is too small, the luminance maysometimes decrease, or phosphor particles may sometimes undergoaggregation. On the other hand, if the weight-average median diameterD₅₀ is too large, non-uniform coating or clogging of e.g. a dispenser islikely to occur.

In the present invention, the weight-average median diameter D₅₀ of thephosphor can be measured, for example, by using an apparatus such as alaser diffraction/scattering type particle size distribution-measuringapparatus.

<Specific Surface Area>

It is preferred that the specific surface area of the phosphor of thepresent invention is usually at most 1.3 m²/g, preferably at most 1.1m²/g, particularly preferably at most 1.0 m²/g and usually at least 0.05m²/g, preferably at least 0.1 m²/g. If the specific surface area of thephosphor is too small, the phosphor particles are large, wherebynon-uniform coating or clogging of e.g. a dispenser tends to occur, andif it is too large, the phosphor particles are small, whereby thecontact area with exterior increases, and the durability tend to bepoor.

In the present invention, the specific surface area of the phosphor canbe measured, for example, by a BET one point method by using e.g. afully automatic specific surface area-measuring apparatus (flow method)(AMS1000A) manufactured by Ohkura Riken Co., Ltd.

<Particle Size Distribution>

It is preferred that the phosphor of the present invention has one peakvalue in its particle size distribution.

Presence of two or more peak values indicates that there are a peakvalue by single particles and a peak value by their aggregates.Therefore, the presence of two or more peak values means that singleparticles are very small.

Thus, a phosphor having one peak value in its particle size distributionis one wherein single particles are large and aggregates are verylittle. Accordingly, there will be an effect such that the luminance isimproved or an effect such that as single particles are grown large, thespecific surface area becomes small, whereby the durability is improved.

In the present invention, the particle size distribution of the phosphorcan be measured, for example, by a laser diffraction/scattering typeparticle size distribution-measuring apparatus (LA-300) manufactured byHORIBA, Ltd. In the measurement, the phosphor is dispersed by usingethanol as a dispersion solvent, then the initial transmittance on theoptical axis is adjusted to about 90%, and the measurement is preferablycarried out by suppressing the influence by aggregation to the minimumwhile stirring the dispersion solvent by a magnet stirrer.

Further, the width of the peak of the above particle size distributionis preferably narrow. Specifically, the quantile deviation (QD) of theparticle size distribution of phosphor particles is usually at least0.18, preferably at least 0.20 and usually at most 0.60, preferably atmost 0.40, more preferably at most 0.35, further preferably at most0.30, particularly preferably 0.25.

Here, the quantile deviation of the particle size distribution becomessmall as particle sizes of phosphor particles are uniform. That is, thequantile deviation of the particle size distribution being small meansthat the width of a peak of the particle size distribution is narrow,and the size of phosphor particles is uniform.

Further, the quantile deviation of the particle size distribution can becalculated by using a particle size distribution curve measured by usinga laser diffraction/scattering type particle size distribution-measuringapparatus.

<Particle Shape>

The particle shape of the phosphor of the present invention as observedfrom a SEM photograph of the present invention is preferably a granularshape uniformly grown in triaxial directions. When the granular shape isuniformly grown in triaxial directions, the specific surface areabecomes small, whereby the contact area with exterior is small, and thedurability will be excellent.

Here, such a SEM photograph may be taken, for example, by SEM (S3400N)manufactured by Hitachi, Ltd.

<Other Characteristics>

Further, in a case where the phosphor is a fluoride complex phosphor,the thermally decomposed fluorine amount per 1 g of the phosphor at 200°C. (hereinafter sometimes referred to as “thermally decomposed Famount”) may become at least 0.01 μg/min, further at least 1 μg/min.However, as described hereinafter, by adopting a specific light emittingdevice structure, it becomes possible to suppress deterioration withtime when the light emitting device is stored or operated in a hightemperature and high humidity state (e.g. at a temperature of 85° C.under a humidity of 85%). Here, the thermally decomposed F amount per 1g of the phosphor is preferably at most 2 μg/min from the environmentalstandard. Further, in order to minimize damage to the circumference ofthe phosphor, a phosphor having a thermally decomposed F amount of atmost 1.5 μg/min is suitably used.

Such a thermally decomposed F amount can be measured by the followingmethod. A predetermined amount of a phosphor is accurately weighed andput in a platinum boat and then set in an alumina core tube of ahorizontal electric furnace. Then, while circulating argon gas at a flowrate of 400 ml/min, the temperature in the furnace is raised and whenthe temperature of the phosphor becomes 200° C., it is maintained fortwo hours. Here, the total amount of argon gas circulated in the furnaceis absorbed by a KOH aqueous solution (concentration: 67 mM), and theabsorbed solution is analyzed by a liquid chromatography method, toobtain the thermally decomposed F amount per minute per 1 g of thephosphor.

Further, in a case where the above red emitting phosphor is a fluoridecomplex phosphor, if it is one having a solubility of at most 7 g in 100g of water at a room temperature of 20° C., as described hereinafter, itbecomes possible to suppress deterioration with time when the lightemitting device is stored or operated in a high temperature and highhumidity state (e.g. at a temperature of 85° C. under a humidity of 85%)by adopting a specific light emitting device structure. Further, in thecase of a fluoride complex phosphor, the solubility in 100 g of water ata room temperature of 20° C. is usually at least 0.005 g, preferably atleast 0.010 g, more preferably at least 0.015 g.

For reference, solubilities of hexafluoro complexes are shown in thefollowing Table. The values disclosed in the Table are based on MaterialSafety Data Sheet (MSDS) attached to the reagents manufactured by MoritaChemical Industries Co., Ltd.

SOLUBILITIES OF HEXAFLUORO COMPLEXES Fluorides Solubility (g/100 g ofwater) K₂TiF₆ 1.28 (20° C.) Na₂TiF₆ 6.5 (20° C.) K₂SiF₆ 0.12 (17.5° C.),0.95 (100° C.) Na₂SiF₆ 0.44 (0° C.), 2.45 (100° C.) K₂ZrF₆ 1.41 (15° C.)Na₂ZrF₆ 0.378 (18° C.) BaSiF₆ 0.026 (17° C.), 0.09 (100° C.) K₃AlF₆0.0385 (16° C.) Na₃AlF₆ 0.039 (25° C.)

(2-2-2-3) Process for Producing Phosphor

The process for producing the phosphor of the present invention is notparticularly limited, but it is generally classified into a method ofemploying a poor solvent as in the following method (1) and a method ofnot using a poor solvent as in the following method (2) (specificallythe following method (2-1) or (2-2)).

(1) Poor solvent separation method

(2) Method of mixing at least two solutions each containing at least oneelement selected from the group consisting of K, Na, Si, Mn and F andthen obtaining a precipitate (phosphor) precipitated by the mixing

In the above method (2), it is preferred that all elements constitutingthe desired phosphor are contained in the solutions to be mixed, and asa combination of the solutions to be mixed, the following (2-1) and(2-2) may specifically be mentioned.

(2-1) Method of mixing a solution containing at least Si and F with asolution containing at least K (and/or Na), Mn and F

(2-2) Method of mixing a solution containing at least Si, Mn and F witha solution containing at least K (and/or Na) and F

Now, the respective production methods will be described with referenceto a typical example wherein M^(IV)′ contains only Si.

(1) Poor Solvent Separation Method

This method is, for example, as disclosed in Example II-1-1 givenhereinafter, a method wherein as raw material compounds e.g. M^(I′) ₂SiF₆ and M^(I′) ₂ RF₆ are used (wherein M^(I)′ and R are as defined inthe above formula (1′)), and these compounds are added in predeterminedproportions into hydrofluoric acid and dissolved and reacted withstirring, and thereafter, a poor solvent for the phosphor is added toprecipitate the phosphor. For example, this method can be carried out inthe same manner as the method disclosed in U.S. Pat. No. 3,576,756.

As mentioned above, by the method disclosed in U.S. Pat. No. 3,576,756,there is a problem such that the phosphor particles obtainable are fineand the luminance is also low, such being practically not useful. Thepresent inventors have found it possible to obtain the desired phosphorby not introducing the poor solvent all at once to precipitate thephosphor by adding such a poor solvent, but slowing down the additionrate of the poor solvent or adding it dividedly.

The combination of the raw material compounds to be used for this poorsolvent separation method is preferably a combination of K₂ SiF₆ and K₂MnF₆, a combination of K₂ SiF₆ and KMnO₄, or a combination of K₂ SiF₆and K₂ MnCl₆.

The combination of K₂ SiF₆ and K₂ MnF₆ may specifically be a combinationof a water-soluble K salt (such as KF, KHF₂, KOH, KCl, KBr, KI,potassium acetate, K₂ CO₃ or the like, the same applies hereinafter),hydrofluoric acid, an aqueous H₂ SiF₆ solution and K₂ MnF₆, acombination of the water-soluble K salt, hydrofluoric acid, a silicate(such as SiO₂, Si alkoxide or the like, the same applies hereinafter)and K₂ MnF₆, or a combination of potassium silicate (K₂ SiO₃),hydrofluoric acid and K₂ MnF₆.

The combination of K₂ SiF₆ and KMnO₄ may specifically be a combinationof the water-soluble K salt, hydrofluoric acid, an aqueous H₂ SiF₆solution and KMnO₄, a combination of the water-soluble K salt,hydrofluoric acid, a silicate and KMnO₄, or a combination of potassiumsilicate (K₂SiO₃), hydrofluoric acid and KMnO₄.

The combination of K₂ SiF₆ and K₂ MnCl₆ may specifically be acombination of the water-soluble K salt, hydrofluoric acid, an aqueousH₂ SiF₆ solution and K₂ MnCl₆, a combination of the water-soluble Ksalt, hydrofluoric acid, a silicate and K₂ MnCl₆, and a combination ofpotassium silicate (K₂ SiO₃), hydrofluoric acid and K₂ MnCl₆.

Here, the above water-soluble K salt or a water-soluble potassium saltin the after-mentioned method (2-1) or (2-2) is a potassium salt havinga solubility of at least 10 wt % in water at 15° C.

These raw material compounds are used in such proportions that aphosphor of a desired composition can be obtained. However, as mentionedabove, there will be a certain deviation between the charged compositionof the phosphor raw materials and the composition of the obtainedphosphor, and it is important to make adjustment so that the compositionof the obtained phosphor would be the desired composition.

Hydrogen fluoride is used in the form of an aqueous solution wherein itsconcentration is usually at least 10 wt %, preferably at least 20 wt %,more preferably at least 30 wt % and usually at most 70 wt %, preferablyat most 60 wt %, more preferably at most 50 wt %. For example, when thehydrofluoric acid concentration is from 40 to 50 wt %, it is preferredto employ it so that the amount of hydrofluoric acid (concentration: 40to 50 wt %) to 1 g of K₂ SiF₆ would be about from 30 to 60 ml.

The reaction can be carried out under atmospheric pressure at roomtemperature (20 to 30° C.).

Usually, raw material compounds are added and mixed in predeterminedproportions to hydrofluoric acid, and after the raw material compoundsare all dissolved, the poor solvent is added.

As the poor solvent, an organic solvent having a solubility parameter ofat least 10 and less than 23.4, preferably from 10 to 15, is usuallyemployed. Here, the solubility parameter is one defined as follows.

(Definition of Solubility Parameter)

By a regular solution theory, the force acting between a solvent and asolute is modeled to be only an intermolecular force, and theinteraction to flocculate liquid molecules can be considered to be onlythe intermolecular force. The cohesive energy of a liquid is equivalentto the vaporization enthalpy, and accordingly, the solubility parameteris defined by δ=√(ΔH/V−RT) where ΔH is the molar heat of vaporizationand V is the molar volume. That is, it is calculated from the squareroot (cal/cm³)^(1/2) of the heat of vaporization required to vaporize 1mol volume of the liquid.

It is rare that a practical solution is a regular solution, and betweensolvent and solute molecules, a force other than the intermolecularforce, such as a hydrogen bond will act, and whether the two componentswill undergo mixing or phase separation, is thermodynamically determinedby a difference between the mixing enthalpy and the mixing entropy ofsuch components. However, on an empirical basis, materials havingsimilar solubility parameters (hereinafter sometimes referred to as “SPvalue”) tend to be easily mixed. Therefore, the SP value will be anindex to judge the mixing efficiency of a solute and a solvent.

By a regular solution theory, the force acting between a solvent and asolute is assumed to be only the intermolecular force, and thesolubility parameter is used as an index to represent the intermolecularforce. A real solution may not necessarily be a regular solution, but itis empirically known that as the difference in the SP value between thetwo components is small, the solubility will be large.

Such a poor solvent may, for example, be acetone (solubility parameter:10.0), isopropanol (solubility parameter: 11.5), acetonitrile(solubility parameter: 11.9), dimethylformamide (solubility parameter:12.0), acetic acid (solubility parameter: 12.6), ethanol (solubilityparameter: 12.7), cresol (solubility parameter: 13.3), formic acid(solubility parameter: 13.5), ethylene glycol (solubility parameter:14.2), phenol (solubility parameter: 14.5) or methanol (solubilityparameter: 14.5 to 14.8). Among them, acetone is preferred since itcontains no hydroxyl group (—OH) and is well soluble in water. Such poorsolvents may be used alone or in combination as a mixture of two or moreof them.

The amount of the poor solvent to be used, varies depending upon itstype, but it is usually at least 50 vol %, preferably at least 60 vol %,more preferably at least 70 vol % and usually at most 200 vol %,preferably at most 150 vol %, more preferably at most 120 vol %, basedon the phosphor material-containing hydrofluoric acid.

Addition of the poor solvent may be dividedly or continuously. However,as the rate of addition of the poor solvent to the phosphor rawmaterial-containing hydrofluoric acid, it is preferred to adopt arelatively slow addition rate i.e. usually at most 400 ml/hr, preferablyfrom 100 to 350 ml/hr, with a view to obtaining the desired phosphorhaving a small specific surface area and high luminance. However, ifthis addition rate is excessively slow, the productivity will beimpaired.

The phosphor precipitated by the addition of the poor solvent isrecovered by solid-liquid separation by e.g. filtration and washed witha solvent such as ethanol, water or acetone. Thereafter, moistureadsorbed to the phosphor is evaporated at a temperature of usually atleast 100° C., preferably at least 120° C., more preferably at least150° C. and usually at most 300° C., preferably at most 250° C., morepreferably at most 200° C. The drying time is not particularly limited,but it is for example at a level of from 1 to 2 hours.

(2-1) Method of Mixing a Solution Containing at Least Si and F with aSolution Containing at Least K, Mn and F to Precipitate the Product(Phosphor).

This method is characterized in that no poor solvent is used, and sincea flammable organic solvent is not used as a poor solvent, industrialsafety will be improved; since no organic solvent is used, the cost canbe reduced; hydrofluoric acid required at the time of synthesizing thesame amount of a phosphor, can be reduced to about one tenth as comparedwith the above-mentioned method (1), whereby further reduction of thecost can be made; as compared with the above method (1), particle growthis further accelerated, and it is possible to obtain a phosphor having asmall specific surface area, a large particle size, excellent durabilityand high luminance.

A solution containing at least Si and F (hereinafter sometimes referredto as “solution I”) is hydrofluoric acid containing the SiF₆ source.

The SiF₆ source in this solution I may be one which is a compoundcontaining Si and F and is excellent in solubility in the solution, andit may, for example, be H₂ SiF₆, Na₂SiF₆, (NH₄)₂ SiF₆, Rb₂ SiF₆ or Cs₂SiF₆. Among them, H₂ SiF₆ is preferred since the solubility in water ishigh, and it contains no alkali metal element as an impurity. These SiF₆sources may be used alone or in combination as a mixture of two or moreof them.

The hydrogen fluoride concentration in hydrofluoric acid of thissolution I is usually at least 10 wt %, preferably at least 20 wt %,more preferably at least 30 wt % and usually at most 70 wt %, preferablyat most 60 wt %, more preferably at most 50 wt %. Further, the SiF₆source concentration is usually at least 10 wt %, preferably at least 20wt % and usually at most 60 wt %, preferably at most 40 wt %. If thehydrogen fluoride concentration in the solution I is too low, when theafter-mentioned solution containing a Mn source is added to the solutionI, Mn ions tend to be hydrolyzed, and the concentration of Mn to beactivated changes, whereby the activated amount of Mn in the synthesizedphosphor tends to be hardly controlled, and fluctuation in the emissionefficiency of the phosphor tends to be large, and if it is too high, theoperational risk tends to be high. Further, if the SiF₆ sourceconcentration is too low, the yield of the phosphor tends to decrease,and at the same time, the grain growth of the phosphor tends to besuppressed, and if it is too high, the phosphor particles tend to be toolarge.

On the other hand, a solution containing at least K, Mn and F(hereinafter sometimes referred to as “solution II”) is hydrofluoricacid containing a K source and a Mn source.

As the K source in the solution II, it is possible to use awater-soluble potassium salt such as KF, KHF₂, KOH, KCl, KBr, KI,potassium acetate or K₂ CO₃. Among them, KHF₂ is preferred, since it canbe dissolved without lowering the hydrogen fluoride concentration in thesolution, and the safety is high since the dissolution heat is small.

Further, as the Mn source in the solution II, it is possible to use, forexample, K₂ MnF₆, KMnO₄ or K₂ MnCl₆. Among them, K₂ MnF₆ is preferred,since it does not contain a Cl element which tends to distort andinstabilize a crystal lattice, whereby it can be present stably inhydrofluoric acid as MnF₆ complex ions while maintaining the oxidationnumber (tetravalent) to be activated. Further, among Mn sources, onecontaining K may serve also as a K source.

These K sources and Mn sources may respectively be used alone or incombination as a mixture of two or more of them.

The hydrogen fluoride concentration in this hydrofluoric acid ofsolution II is usually at least 10 wt %, preferably at least 20 wt %,more preferably at least 30 wt % and usually at most 70 wt %, preferablyat most 60 wt %, more preferably at most 50 wt %. Further, the totalconcentration of the K source and the Mn source is usually at least 5 wt%, preferably at least 10 wt %, more preferably at least 15 wt % andusually at most 45 wt %, preferably at most 40 wt %, more preferably atmost 35 wt %. If the hydrogen fluoride concentration is too low, the rawmaterial K₂ MnF₆ for an activated element contained in the solution IItends to be unstable and tends to be hydrolysable, and the Mnconcentration changes vigorously, whereby the activated amount of Mn inthe phosphor to be synthesized tends to be hardly controlled, andfluctuation in the emission efficiency of the phosphor tends to belarge, and if it is too high, the operational risk tends to be high. Onthe other hand, if the K source and Mn source concentration is too low,the yield of the phosphor tends to decrease, and at the same time, thegrain growth of the phosphor tends to be suppressed, and if it is toohigh, the phosphor particles tend to be too large.

The method of mixing the solution I and the solution II is notparticularly limited. While stirring the solution I, the solution II maybe added and mixed, or while stirring the solution II, the solution Imay be added and mixed. Otherwise, the solution I and the solution IImay be put into a container all at once and mixed with stirring.

By mixing the solution I and the solution II, the SiF₆ source, the Ksource and the Mn source are reacted in a prescribed ratio, wherebycrystals of the desired phosphor will precipitate. The crystals arerecovered by solid-liquid separation by e.g. filtration and washed witha solvent such as ethanol, water or acetone. Thereafter, moistureadsorbed to the phosphor is evaporated at a temperature of usually atleast 100° C., preferably at least 120° C., more preferably at least150° C. and usually at most 300° C., preferably at most 250° C., morepreferably at most 200° C. The drying time is not particularly limited,but it may, for example, be at a level of from 1 to 2 hours.

Also at the time of this mixing of the solution I and the solution II,it is necessary to adjust the mixing ratio of the solution I and thesolution II so that the composition of the phosphor as the product wouldbe the desired composition, taking into consideration the deviationbetween the above-mentioned charged composition of the phosphor rawmaterial and the composition of the obtainable phosphor.

(2-2) Method of Mixing a Solution Containing at Least Si, Mn and F witha Solution Containing at Least K and F to Precipitate a Product(Phosphor)

Also this method is characterized in that no poor solvent is used, andthere are the same merits as in the above method (2-1).

Further, according to this method (2-2), K₂ MnF₆ is dissolved in thesolution, and therefore, as compared with the above method (2-1), Mn canbe uniformly activated. Therefore, the concentration of Mn to beactually activated can be linearly controlled against the chargedcomposition of the Mn concentration, and thus, there is a merit that thequality control can easily be carried out on an industrial scale.

A solution containing at least Si, Mn and F (hereinafter sometimesreferred to as “solution III”) is hydrofluoric acid containing a SiF₆source and a Mn source.

The SiF₆ source of the solution III may be one which is a compoundcontaining Si and F and is excellent in solubility in the solution, andit may, for example, be H₂ SiF₆, Na₂SiF₆, (NH₄)₂ SiF₆, Rb₂ SiF₆ or Cs₂SiF₆. Among them, H₂ SiF₆ is preferred, since the solubility in water ishigh, and it contains no alkali metal element as an impurity. These SiF₆sources may be used alone or in combination as a mixture of two or moreof them.

As the Mn source of the solution III, K₂ MnF₆, KMnO₄, K₂ MnCl₆ may, forexample, be used. Among them, K₂ MnF₆ is preferred, since it does notcontain a Cl element which tends to distort and instabilize a crystallattice, whereby it can be stably present in the HF aqueous solution asMnF₆ complex ions while maintaining the oxidation number (tetravalent)to be activated. Among such Mn sources, one containing K may serve alsoas a K source. Such Mn sources may be used alone or in combination as amixture of two or more of them.

The hydrogen fluoride concentration in this hydrofluoric acid of thesolution III is usually at least 10 wt %, preferably at least 20 wt %,more preferably at least 30 wt % and usually at most 70 wt %, preferablyat most 60 wt %, more preferably at most 50 wt %. Further, the SiF₆source concentration is usually at least 10 wt %, preferably at least 20wt %, and usually at most 60 wt %, preferably at most 40 wt %. Further,the Mn source concentration is usually at least 0.1 wt %, preferably atleast 0.3 wt %, more preferably at least 1 wt % and usually at most 10wt %, preferably at most 5 wt %, more preferably at most 2 wt %. If thehydrogen fluoride concentration in the solution III is too low, Mn ionstend to be easily hydrolyzed, and whereby the concentration of Mn to beactivated will change, and it tends to be difficult to control theactivated amount of Mn in the synthesized phosphor, and fluctuation inthe emission efficiency of the phosphor tends to be large. On the otherhand, if the hydrogen fluoride concentration is too high, theoperational risk tends to be high. Further, if the SiF₆ sourceconcentration is too low, the yield of the phosphor tends to decrease,and at the same time, the grain growth of the phosphor tends to besuppressed, and if it is too high, the phosphor particles tend to be toolarge. Further, if the Mn concentration is too low, the yield of thephosphor tends to decrease, and at the same time, the grain growth ofthe phosphor tends to be suppressed, and if it is too high, the phosphorparticles tends to be too large.

On the other hand, a solution containing at least K and F (hereinaftersometimes referred to as “solution IV”) is hydrofluoric acid containinga K source.

As the K source in the solution IV, it is possible to use awater-soluble potassium salt such as KF, KHF₂, KOH, KCl, KBr, KI,potassium acetate or K₂ CO₃. Among them, KHF₂ is preferred, since it canbe dissolved without lowering the hydrogen fluoride concentration in thesolution, and the dissolution heat is small, and the safety is high.Such K sources may be used alone or in combination as a mixture of twoor more of them.

The hydrogen fluoride concentration in this hydrofluoric acid of thesolution IV is usually at least 10 wt %, preferably at least 20 wt %,more preferably at least 30 wt % and usually at most 70 wt %, preferablyat most 60 wt %, more preferably at most 50 wt %. Further, the K sourceconcentration is usually at least 5 wt %, preferably at least 10 wt %,more preferably at least 15 wt % and usually at most 45 wt %, preferablyat most 40 wt %, more preferably at most 35 wt %. If the hydrogenfluoride concentration is too low, when added to the solution III, theraw material K₂MnF₆ for an activated element contained in the solutionIII tends to be unstable and tends to be hydrolyzed, whereby the Mnconcentration changes vigorously, and it becomes difficult to controlthe activated amount of Mn in the synthesized phosphor, and fluctuationin the luminous efficiency of the phosphor tends to be large, and if itis too high, the operational risk tends to be high. Further, if the Ksource concentration is too low, the yield of the phosphor tends todecrease, and at the same time, the grain growth of the phosphor tendsto be suppressed, and if it is too high, the phosphor particles tend tobe too large.

Further, if the Mn concentration is too low, the yield of the phosphortends to decrease, and at the same time, the grain growth of thephosphor tends to be suppressed, and if it is too high, the phosphorparticles tend to be too large.

The method of mixing the solution III and the solution IV is notparticularly limited, and while stirring the solution III, the solutionIV may be added and mixed, or while stirring the solution IV, thesolution III may be added and mixed. Otherwise, the solution III and thesolution IV may be put into a container all at once and mixed withstirring.

By mixing the solution III and the solution IV, the SiF₆ source, the Mnsource and the K source are reacted in a prescribed ratio, wherebycrystals of the desired phosphor will precipitate. The crystals arerecovered by solid-liquid separation by e.g. filtration and washed witha solvent such as ethanol, water or acetone. Thereafter, moistureadsorbed to the phosphor is evaporated at a temperature of usually atleast 100° C., preferably at least 120° C., more preferably at least150° C. and usually at most 300° C., preferably at most 250° C., morepreferably at most 200° C. The drying time is not particularly limited,but it may, for example, be at a level of from 1 to 2 hours.

Also at the time of this mixing of the solution III and the solution IV,it is necessary to adjust the mixing ratio of the solution III and thesolution IV so that the composition of the phosphor as the product wouldbe the desired composition, taking into consideration the deviationbetween the above-mentioned charged composition of the phosphor rawmaterial and the composition of the obtainable phosphor.

(2-2-2-4) Application of Phosphor

The phosphor of the present invention can be used in an optionalapplication to use a phosphor. Further, the phosphor of the presentinvention may be used alone, but it is possible to use it in the form ofa mixture of phosphors in an optional combination, i.e. two or morephosphors of the present invention may be used in combination, or aphosphor of the present invention may be used in combination withanother phosphor.

Further, the phosphor of the present invention may suitably be used forvarious light emitting devices taking an advantage of the characteristicsuch that it can be excited with blue light. The phosphor of the presentinvention is usually a red emitting phosphor. Accordingly, for example,by combining the phosphor of the present invention with an excitationlight source which emits blue light, it is possible to produce a purpleto pink color-emitting device. Further, by combining the phosphor of thepresent invention with an excitation light source which emits blue lightand a phosphor which emits green light, or with an excitation lightsource which emits near ultraviolet light, a phosphor which emits bluelight and a phosphor which emits green light, the phosphor of thepresent invention will be excited by blue light from the excitationlight source which emits blue light or from the phosphor which emitsblue light, to emit red light, whereby it is possible to produce a whitelight emitting device (the after-mentioned “light emitting device of thepresent invention”).

The emission color of the light emitting device is not limited to whitecolor, and by suitably selecting the combination or contents ofphosphors, it is possible to produce a light emitting device which emitsa bulb color (warm white color) or a pastel color. A light emittingdevice thus obtained can be used as an illuminating device or a lightemitting portion of an image display device (particularly a backlightfor liquid crystal or the like).

(2-2-3) Green Emitting Phosphor

As the green emitting phosphor to be used for the phosphor film orphosphor layer to be used for a color image display device of thepresent invention, it is possible to use various phosphors having atleast one emission peak wavelength in a wavelength region of preferablyfrom 515 to 550 nm, more preferably from 515 to 535 nm. As the greenemitting phosphor to realize an image having such a high color purity,an oxynitride phosphor, a sialon phosphor, an aluminate phosphor or anorthosilicate phosphor may, for example, be mentioned. Among them, aneuropium and/or cerium-activated oxynitride phosphor, aneuropium-activated sialon phosphor, an europium-activated Mn-containingaluminate phosphor, or an europium-activated orthosilicate phosphor, ispreferred.

Now, specific examples of preferably employed green emitting phosphorswill be described.

(2-2-3-1) Europium and/or Cerium-Activated Oxynitride Phosphor

As another example of the green emitting phosphor, a compoundrepresented by the following formula (G6) may be mentioned.

M1_(x)Ba_(y)M2_(z)L_(u)O_(v)N_(w)  (G6)

In the above formula (G6), M1 is at least one activated element selectedfrom the group consisting of Cr, Mn, Fe, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho,Er, Tm and Yb, M2 is at least one bivalent metal element selected fromthe group consisting of Sr, Ca, Mg and Zn, L is a metal element selectedfrom metal elements belonging to Groups 4 and 14 of the Periodic Table,and x, y, z, u, v and w are numerical values within the followingranges, respectively:

0.00001≦x≦3,

0≦y≦2.99999,

2.6≦x+y+z≦3,

0≦u≦11,

6<v≦25, and

0<w≦17.

In the formula (G6), M1 is an activated element.

As M1, in addition to Eu, at least one transition metal element or rareearth element selected from the group consisting of Cr, Mn, Fe, Ce, Pr,Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb may be mentioned. M1 may contain anyone of these elements alone or may contain two or more of them in anoptional combination or ratio. Among them, in addition to Eu, Ce, Sm, Tmor Yb as a rare earth element, may be mentioned as a preferred element.Further, the above M1 preferably contains at least Eu or Ce among them,from the viewpoint of luminescent quantum efficiency. Among them, onecontaining at least Eu is more preferred from the viewpoint of theemission peak wavelength, and it is particularly preferred to employonly Eu.

The activated element M1 will be present in the form of a bivalentcation and/or a trivalent cation in the phosphor of the presentinvention. At that time, the activated element M1 preferably has ahigher proportion of the bivalent cation. In a case where M1 is Eu, theproportion of Eu²⁺ based on the entire amount of Eu is specificallyusually at least 20 mol %, preferably at least 50 mol %, more preferablyat least 80 mol %, particularly preferably at least 90 mol %.

Here, the proportion of Eu²⁺ in the entire Eu contained in the phosphorof the present invention may be examined, for example, by themeasurement of the X-ray absorption fine structure. Namely, when the L3absorption edge of Eu atoms is measured, Eu²⁺ and Eu³⁺ show separateabsorption peaks, and their ratio can be determined from the peak areas.Further, the proportion of Eu²⁺ in the entire Eu contained in thephosphor of the present invention may be also known by the measurementof electron spin resonance (ESR).

Further, in the formula (G6), x is a numerical value within a range of0.00001≦x≦3. Within such a range, x is preferably at least 0.03, morepreferably at least 0.06, particularly preferably at least 0.12. On theother hand, if the content of the activated element M1 is too large, theconcentration quenching is likely to result, and accordingly, x ispreferably at most 0.9, more preferably at most 0.7, particularlypreferably at most 0.45.

Further, in the phosphor of the present invention, the sites of Ba maybe substituted by Sr, Ca, Mg and/or Zn, while the after-mentionedspecific phase crystal structure (hereinafter sometimes referred to as“the BSON phase crystal structure”) is maintained. Accordingly, in theabove formula (G6), M2 is at least one bivalent metal element selectedfrom the group consisting of Sr, Ca, Mg and Zn. At that time, M2 ispreferably Sr, Ca and/or Zn, more preferably Sr and/or Ca, furtherpreferably Sr. Further, Ba and M2 may further be partially substitutedby such metal element ions.

Further, M2 may contain any one of these elements alone or may containtwo or more of them in an optional combination or ratio.

In the substitution by Ca ions, the proportion of Ca based on the totalamount of Ba and Ca is preferably at most 40 mol %. If the amount of Caexceeds this proportion, the emission wavelength tends to shift to thelong wavelength side, whereby the emission peak intensity is likely todecrease.

In the substitution by Sr ions, the proportion of Sr based on the totalamount of Ba and Sr is preferably at most 50 mol %. If the amount of Srexceeds this proportion, the emission wavelength tends to shift to thelong wavelength side, and the emission peak intensity is likely todecrease.

In the substitution by Zn ions, the proportion of Zn based on the totalamount of Ba and Zn is preferably at most 60 mol %. If the amount of Znexceeds this proportion, the emission wavelength tends to shift to thelong wavelength side, and the emission peak intensity is likely todecrease.

Accordingly, in the formula (G6), the amount of z may be set dependingupon the type of the metal element M2 and the amount of y. Specifically,in the formula (G6), y is a numerical value within a range of0≦y≦2.9999. Further, in the formula (G6), x+y+z is 2.6≦x+y+z≦3.

In the phosphor of the present invention, Ba or M2 element may sometimesbe deficient together with oxygen or nitrogen. Accordingly, in theformula (G6), the value of x+y+z may sometimes be less than 3, and x+y+zmay usually take a value of 2.6≦x+y+z≦3, but ideally x+y+z=3.

Further, the phosphor of the present invention preferably contains Bafrom the viewpoint of the stability of the crystal structure. Thus, inthe above formula (G6), y is preferably larger than 0, more preferablyat least 0.9, particularly preferably at least 1.2, and, from therelation to the content of activating elements, it is preferably smallerthan 2.99999, more preferably at most 2.99, further preferably at most2.98, particularly preferably at most 2.95.

In the formula (G6), L represents a metal element selected from metalelements in Group 4 of the Periodic Table such as Ti, Zr and Hf andmetal elements in Group 14 of the Periodic Table such as Si and Ge.Here, L may contain any one of such metal elements alone or may containtwo or more of them in an optional combination or ratio. Here, L ispreferably Ti, Zr, Hf, Si or Ge, more preferably Si or Ge, particularlypreferably Si. Here, L may partially contain metal elements capable ofbecoming trivalent cations such as B, Al and Ga, so long as no adverseeffects are given to the performance of the phosphor from the viewpointof the electrical charge balance of the crystal of the phosphor. Thecontent of such metal elements is usually at most 10 atomic %,preferably at most 5 atomic %, based on L.

Further, in the formula (G6), u is a numerical value of usually at most11, preferably at most 9, more preferably at most 7 and usually largerthan 0, preferably at least 3, more preferably at least 5.

The amounts of 0 ions and N ions are represented by numerical values vand w in the formula (G6). Specifically, in the formula (G6), v is anumerical value of usually larger than 6, preferably larger than 7, morepreferably larger than 8 and further preferably larger than 9,particularly preferably larger than 11, and a numerical value of usuallyat most 25, preferably smaller than 20, more preferably smaller than 15,further preferably smaller than 13.

Further, the phosphor of the present invention is an oxynitride, andtherefore, N is an essential component. Thus, in the formula (G6), w isa numerical value larger than 0. Further, w is a numerical value ofusually at most 17, preferably smaller than 10, more preferably smallerthan 4, further preferably smaller than 2.4.

Accordingly, from the above described viewpoint, in the formula (G6), u,v and w are particularly preferably 5≦u≦7, 9<v<15 and 0<w<4,respectively. It is thereby possible to increase the emission peakintensity of the phosphor.

Further, in the phosphor of the present invention, the proportion ofoxygen atoms to metal elements such as (M1+Ba+M2) and L is preferablylarger than the proportion of nitrogen atoms, and the amount of nitrogenatoms to the amount of oxygen atoms (N/O) is at most 70 mol %,preferably at most 50 mol %, more preferably at most 30 mol %, furtherpreferably less than 20 mol %. Further, the lower limit is usuallylarger than 0 mol %, preferably at least 5 mol %, more preferably atleast 10 mol %.

Specific examples of preferred compositions of the phosphor of thepresent invention will be given below, but it should be understood thatthe composition of the phosphor of the present invention is by no meansrestricted to the following examples.

In the following examples, the composition in the brackets means acomposition comprising at least one of elements divided by a comma (,).For example,

(Ca,Sr,Ba)₃(Si,Ge)₆O₁₂N₂:(Eu,Ce,Mn) represents a phosphor whichcomprises at least one atom selected from the group consisting of Ca, Srand Ba, at least one atom selected from the group consisting of Si andGe, O and N and which is further activated by at least one atom selectedfrom the group consisting of Eu, Ce and Mn.

A preferred specific example of the green emitting phosphor of thepresent invention may, for example, be(Ca,Sr,Ba)₃(Si,Ge)₆O₁₂N₂:(Eu,Ce,Mn), (Ca,Sr,Ba)₃(Si,Ge)₆O₉N₄:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₆O₃N₈:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₇O₁₂N_(8/3):(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₈O₁₂N_(14/3):(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₈O₁₂N₆:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)_(28/3)O₁₂N_(22/3):(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)_(29/3)O₁₂N_(26/3):(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)_(6.5)O₁₃N₂:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₇O₁₄N₂:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₈O₁₆N₂:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₉O₁₈N₂:(Eu,Ce,Mn),(Ca,Sr,Ba)₃(Si,Ge)₁₀O₂₀N₂:(Eu,Ce,Mn) or(Ca,Sr,Ba)₃(Si,Ge)₁₁O₂₂N₂:(Eu,Ce,Mn), and a more preferred example may,for example, be Ba₃Si₆O₁₂N₂:Eu, Ba₃Si₆O₉N₄:Eu, Ba₃Si₆O₃N₈:Eu,Ba₃Si₇O₁₂N_(8/3):Eu, Ba₃Si₈O₁₂N_(14/3):Eu, Ba₃Si₈O₁₂N₆:Eu,Ba₃Si_(28/3)O₁₂N_(22/3):Eu, Ba₃Si_(29/3)O₁₂N_(26/3):Eu,Ba₃Si_(6.5)O₁₃N₂:Eu, Ba₃Si₇O₁₄N₂:Eu, Ba₃Si₈O₁₆N₂:Eu, Ba₃Si₉O₁₈N₂:Eu,Ba₃Si₁₀O₂₀N₂:Eu, Ba₃Si₁₁O₂₂N₂:Eu, Ba₃Si₆O₁₂N₂:Eu, Mn, Ba₃Si₆O₉N₄:Eu, Mn,Ba₃Si₆O₃N₈:Eu, Mn, Ba₃Si₇O₁₂N_(8/3):Eu, Mn, Ba₃Si₈O₁₂N_(14/3):Eu, Mn,Ba₃Si₈O₁₂N₆:Eu, Mn, Ba₃Si_(28/3)O₁₂N_(22/3):Eu, Mn,Ba₃Si_(29/3)O₁₂N_(26/3):Eu, Mn, Ba₃Si_(6.5)O₁₃N₂:Eu, Mn, Ba₃Si₇O₁₄N₂:Eu,Mn, Ba₃Si₈O₁₆N₂:Eu, Mn, Ba₃Si₉O₁₈N₂:Eu, Mn, Ba₃Si₁₀O₂₀N₂:Eu, Mn,Ba₃Si₁₁O₂₂N₂:Eu, Mn, Ba₃Si₆O₁₂N₂:Ce, Ba₃Si₆O₉N₄:Ce, Ba₃Si₆O₃N₈:Ce,Ba₃Si₇O₁₂N_(8/3):Ce, Ba₃Si₈O₁₂N_(14/3):Ce, Ba₃Si₈O₁₂N₆:Ce,Ba₃Si_(28/3)O₁₂N_(22/3):Ce, Ba₃Si_(29/3)O₁₂N_(26/3):Ce,Ba₃Si_(6.5)O₁₃N₂:Ce, Ba₃Si₇O₁₄N₂:Ce, Ba₃Si₈O₁₆N₂:Ce, Ba₃Si₉O₁₈N₂:Ce,Ba₃Si₁₀O₂₀N₂:Ce or Ba₃Si₁₁O₂₂N₂:Ce.

The above-described oxynitride phosphor to be used in the presentinvention preferably has a specific crystal structure i.e. the BSONphase as defined below.

(2-2-3-1-1) Bson Phase

It is a crystal phase whereby a diffraction peak is observed in a range(R0) of diffraction angle (2θ) of from 26.9 to 28.2° in an X-raydiffraction measurement using an X-ray source of CuKα. Using thediffraction peak (P0) as the standard peak, five diffraction peaks(excluding diffraction peaks within an angle range of from 20.9° to22.9°) led from Bragg angles (θ0) of P0 are designated as P1, P2, P3, P4and P5, respectively, in the sequential order from the low angle side,and when the angle ranges of the diffraction angles of these diffractionpeaks are designated as R1, R2, R3, R4 and R5, R1, R2, R3, R4 and R5show the following angle ranges, respectively:

R1=R1s−R1e,

R2=R2s−R2e,

R3=R3s−R3e,

R4=R4s−R4e,

R5=R5s−R5e.

Further, it is a crystal phase wherein there is at least one diffractionpeak in each of all ranges of R1, R2, R3, R4 and R5, and to the heightof the highest diffraction peak among P0, P1, P2, P3, P4 and P5, theintensity of P0 has an intensity of at least 20% by the ratio in heightof the diffraction peak, and at least one peak intensity of P1, P2, P3,P4 or P5 is at least 5%, preferably at least 9% by the ratio in heightof the diffraction peak.

Here, in a case where two or more diffraction peaks are present withineach of the angle ranges R0, R1, R2, R3, R4 and R5, the peak having thehighest peak intensity among them is taken as P0, P1, P2, P3, P4 and P5,respectively.

Here, R1 s, R2 s, R3 s, R4 s and R5 s represent the start angles of R1,R2, R3, R4 and R5, respectively, R1 e, R2 e, R3 e, R4 e and R5 erepresent end angles of R1, R2, R3, R4 and R5, respectively, and theyrepresent the following angles:

R1s: 2×arcsin {sin(θ0)/(1.994×1.015)}

R1e: 2×arcsin {sin(θ0)/(1.994×0.985)}

R2s: 2×arcsin {sin(θ0)/(1.412×1.015)}

R2e: 2×arcsin {sin(θ0)/(1.412×0.985)}

R3s: 2×arcsin {sin(θ0)/(1.155×1.015)}

R3e: 2×arcsin {sin(θ0)/(1.155×0.985)}

R4s: 2×arcsin {sin(θ0)/(0.894×1.015)}

R4e: 2×arcsin {sin(θ0)/(0.894×0.985)}

R5s: 2×arcsin {sin(θ0)/(0.756×1.015)}

R5e: 2×arcsin {sin(θ0)/(0.756×0.985)}

Further, the phosphor to be used in the present invention may contain animpurity phase of e.g. cristobalite as one crystal form of silicondioxide, α-silicon nitride or β-silicon nitride, in the X-raydiffraction measurement using an X-ray source of CuKα. The content ofsuch impurities can be determined by the X-ray diffraction measurementusing an X-ray source of CuKα. That is, the strongest peak intensity ofthe impurity phase is usually at most 40%, preferably at most 30%, morepreferably at most 20%, further preferably at most 10%, based on thestrongest peak intensity among the above P0, P1, P2, P3, P4 and P5 fromthe results of the X-ray diffraction measurement, and it is particularlypreferred that no peak of such an impurity phase is observed, and theBSON phase is present as a single phase. It is thereby possible toincrease the emission peak intensity.

As the oxynitride phosphor to be used in the present invention, thephosphors disclosed in WO2007/088966 may be used.

Further, another specific example of the green emitting phosphor may,for example, be a Eu²⁺-activated Sr—SiON which has a chemical formula(Sr_(1-m-n)Ca_(n)Ba_(o))Si_(x)N_(y)O_(z):Eu_(m) (wherein m=0.002 to 0.2,n=0.0 to 0.25, o=0.0 to 0.25, x=1.5 to 2.5, y=1.5 to 2.5, and z=1.5 to2.5) and which can be excited by light with a wavelength within a rangeof from UV to blue.

As specific examples of such a phosphor, known phosphors disclosed ine.g. EP1413618, JP-A-2005-530917 and JP-A-2004-134805 may, for example,be mentioned.

(2-2-3-2) SiAlON Phosphor Activated by Europium

Further, another specific example of the green emitting phosphor may,for example, be β-SiAlON activated by europium, or the like, disclosedin “Success in Development of Green Phosphor for White LED”, referencematerial for Science Reporters Association, Reporters Association forthe Ministry of Education, Culture, Sports, Science and Technology,Reporters Association for Tsukuba Kenkyugakuentoshi, Published byIndependent Administrative Institution National Institute for MaterialsScience on Mar. 23, 2005.

(2-2-3-3) Mn-Containing Aluminate Phosphor Activated by Europium

As another specific example of the green emitting phosphor, a compoundrepresented by the following formula (G7) may be mentioned.

R_(1-a)Eu_(a)M_(1-b)Mn_(b)A₁₀O₁₇  (G7)

In the formula (G7), a and b are numbers which respectively satisfy0.05<a≦1, 0.6<a/b<5, and 0.01<b≦0.9, and R is at least one elementselected from the group consisting of Ba, Sr and Ca, M is Mg and/or Zn,and A is at least one element selected from the group consisting of Al,Ga, Sc and B.

In a case where a is at most 0.05, the emission intensity of the crystalphase tends to be low when excited with light having a wavelength of 400nm. A crystal phase having a chemical composition wherein a is a numbersatisfying 0.05<a≦1, is preferred, since the emission intensity is high.For the same reason, a is more preferably 0.1≦a≦1, further preferably0.2≦a≦1, particularly preferably 0.25≦a≦1, most preferably 0.3≦a≦1.

Further, in a case where a/b is at most 0.6, the excitation light havinga wavelength of 400 nm cannot sufficiently be absorbed, whereby theemission intensity from the second phosphor tends to be low. On theother hand, if a/b is at least 5, the blue emission intensity becomesstronger than the green emission intensity, whereby a green emissionwith a good color purity tends to be hardly obtainable. The crystalphase having a chemical composition wherein a/b satisfies 0.6<a/b<5, ispreferred since the ratio of the green emission intensity in thevicinity of a wavelength of 515 nm to the blue emission intensity in thevicinity of a wavelength of 450 nm, is high, the green color purity ishigh, and it is possible to obtain a light emitting device with goodcolor rendering. For the same reason, a/b≧0.8 is preferred, and a/b≧1 ismore preferred. Further, a/b≦4 is preferred, a/b≦3 is more preferred.

The element represented by R in the above formula (G7) is at least oneelement selected from the group consisting of Ba, Sr and Ca, but it ispreferred to have a crystal phase having a chemical composition whereinR is Ba and/or Sr, since a high emission intensity can thereby beobtained. Further, it is more preferred that Ba is at least 50 mol % ofthe entire R, and Sr is at least 10 mol % of the entire R, whereby ahigh emission intensity can be obtained.

The element represented by M in the above formula (G7) is Mg and/or Zn,but it is preferred to have a crystal phase having a chemicalcomposition wherein M is Mg, whereby a high emission intensity can beobtained.

The element represented by A in the above formula (G7) is at least oneelement selected from the group consisting of Al, Ga, Sc and B, but itis preferred to have a crystal phase having a chemical compositionwherein Al is at least 50 mol % of the entire A, with a view toobtaining a high emission intensity. Further, it is more preferred thatAl is at least 99 mol % of the entire A, whereby the emissioncharacteristics will be good.

Among these, a phosphor which contains an alkali metal in the crystalphase of the phosphor having the above composition and wherein thecontent of the alkali metal element is at most 3 mol % to the number ofsites which can be substituted by Eu, is preferred, since it has a highemission intensity and luminance constantly even when the phosphor isexcited with a near ultraviolet light, and it is excellent also in thetemperature characteristics.

Such an alkali metal element is preferably Li, Na or K, particularlypreferably Na or K.

Further, the content of the alkali metal element is preferably at least0.1 mol %, more preferably at least 0.2 mol %, further preferably atleast 0.3 mol %, particularly preferably at least 0.5 mol % andpreferably at most 2.6 mol %, more preferably at most 2.3 mol %, furtherpreferably at most 2 mol %, furthermore preferably at most 1.8 mol %,particularly preferably at most 1.6 mol %.

Further, the above phosphor preferably contains F as an anion element.The content of the element F is larger than 0 mol %, preferably at least0.01 mol %, more preferably at least 0.05 mol %, more preferably atleast 0.1 mol % and usually at most 10 mol %, preferably at most 5 mol%, more preferably at most 3 mol %, based on the number of sites whichmay be substituted by Eu in the crystal phase of the phosphor of theabove composition.

Such a phosphor can be obtained as disclosed also in WO2008/123498, bypermitting a monovalent metal halide to be present at a prescribedconcentration as a flux during firing of the raw material mixture.

Such phosphors are ones, whereby the reduction rate (%) of the emissionpeak intensity at an excitation wavelength of 400 nm to the emissionpeak intensity at an excitation wavelength of 340 nm is at most 29%,preferably at most 26%, more preferably at most 23%, as measured at atemperature of 25° C. Further, they are ones whereby the reduction rateof the emission peak intensity at an excitation wavelength of 390 nm tothe emission peak intensity at an excitation wavelength of 382 nm is atmost 3.1%, preferably at most 2.5%, more preferably at most 2%, furtherpreferably at most 1.5%, as measured at a temperature of 25° C.

Here, the reduction rate of such an emission peak intensity is usuallyat least 0%.

The above excitation spectrum can be measured by using e.g. afluorescence measuring apparatus (manufactured by JASCO Corporation)equipped with a 150 W xenon lamp as an excitation light source and amultichannel CCD detector C7041 (manufactured by Hamamatsu PhotonicsK.K.) as a spectrum measuring device.

(2-2-3-4) Ortho-Silicate Phosphor Activated by Europium

As another specific example of the green emitting phosphor, a compoundrepresented by the following formula (G8) may be mentioned.

(M1_((1-x))M2_(x))_(α)SiO_(β)  (G8)

In the above formula (G8), M1 is at least one element selected from thegroup consisting of Ba, Ca, Sr, Zn and Mg, M2 is at least one metalelement which may take bivalent and trivalent atomic valencies, and x, αand β are numbers satisfying, respectively 0.01<x<0.3, 1.5≦α≦2.5, and3.5≦β≦4.5.

It is particularly preferred that M1 contains at least Ba. In such acase, the molar ratio of Ba based on the entire M1, is usually at least0.5, preferably at least 0.55, more preferably at least 0.6 and usuallyless than 1, preferably at most 0.97, more preferably at most 0.9,particularly preferably at most 0.8.

Further, it is particularly preferred that M1 contains at least Ba andSr. Here, when the molar ratios of Ba and Sr based on the entire M1 arerepresented by [Ba] and [Sr], respectively, the proportion of [Ba] inthe total of [Ba] and [Sr] i.e. the value represented by[Ba]/([Ba]+[Sr]) is usually larger than 0.5, preferably at least 0.6,more preferably at least 0.65 and usually at most 1, preferably at most0.9, more preferably at most 0.8.

Further, the relative ratio of [Ba] to [Sr], i.e. the value representedby [Ba]/[Sr], is usually within a range of larger than 1, preferablylarger than 1.2, more preferably larger than 1.5, further preferablylarger than 1.8 and usually at most 15, preferably at most 10, morepreferably at most 5, further preferably at most 3.5.

Further, in a case where in the formula (G8), M1 contains at least Sr,part of Sr may be substituted by Ca. In such a case, the amount forsubstitution by Ca is usually within a range of at most 10%, preferablyat most 5%, more preferably at most 2%, by a molar ratio of the amountof substituted Ca to the total amount of Sr.

Further, Si may be partially substituted by another element such as Ge.However, from the viewpoint of the green emission intensity, etc., theproportion of Si substituted by another element should better be assmall as possible. Specifically, another element such as Ge may becontained in an amount of not more than 20 mol % of Si, and it is morepreferred that Si is entirely Si without substitution.

In the above formula (G8), M2 is at least one metal element which ismentioned as an activated element and which may take bivalent andtrivalent atomic valencies. Specifically, a transition metal elementsuch as Cr or Mn; or a rare earth element such as Eu, Sm, Tm or Yb, may,for example, be mentioned. M2 may contain any one of such elements aloneor may contain two or more of them in an optional combination or ratio.Among them, as M2, Sm, Eu or Yb is preferred, and Eu is particularlypreferred.

In the formula (G8), x is a number representing the moles of M2, andspecifically, it is usually larger than 0.01, preferably at least 0.04,more preferably at least 0.05, particularly preferably at least 0.06,and usually less than 0.3, preferably at most 0.2, more preferably atmost 0.16.

In the formula (G8), α is preferably close to 2, but it represents anumber of usually at least 1.5, preferably at least 1.7, more preferablyat least 1.8 and usually at most 2.5, preferably at most 2.2, furtherpreferably at most 2.1, particularly preferably 2.

In the formula (G8), β represents a number of usually at least 3.5,preferably at least 3.8, more preferably at least 3.9, and usually atmost 4.5, preferably at most 4.4, more preferably at most 4.1.

Further, a specific composition phosphor may contain, in addition toelements disclosed in the above formula (G8) i.e. in addition to M1, M2,Si (silicon) and O (oxygen), an element (which may sometimes referred toas “a trace element”) selected from the group consisting of an alkalimetal element, an alkaline earth metal element, zinc (Zn), yttrium (Y),aluminum (Al), scandium (Sc), phosphorus (P), nitrogen (N), a rare earthelement, a monovalent element such as a halogen element, a bivalentelement, a trivalent element, a minus monovalent element and a minustrivalent element, and it is particularly preferably one containing analkali metal element or a halogen element.

The total content of the above trace elements is usually at least 1 ppm,preferably at least 3 ppm, further preferably at least 5 ppm and usuallyat most 100 ppm, preferably at most 50 ppm, further preferably at most30 ppm. In a case where the specific composition phosphor containsplural types of trace elements, their total amount is adjusted tosatisfy the above range.

As the phosphor represented by the above formula (G8), one disclosed inWO2007/052405 may be mentioned. Particularly preferred is one obtainedby firing a raw material mixture or phosphor precursor obtainable byfiring it, and further carrying out firing in the presence of SrCl₂ inan amount of at least 0.05 mol by a molar ratio to silicon (Si) in thephosphor, alone or in a further presence of CsCl in an amount of atleast 0.1 mol, as flux, in a strongly reducing atmosphere, since it hasa high external quantum efficiency.

Further, at the time of the firing, it is preferred to carry out thefiring in a strongly reducing atmosphere, for example, in thecoexistence of solid carbon.

Such a phosphor represented by the formula (G8) is one having suchcharacteristics that the half-value width of the emission peak whenexcited with light having a peak wavelength of 400 nm or 455 nm is atmost 75 nm, and the external quantum efficiency as defined by thefollowing formula is at least 0.59, preferably at least 0.60, morepreferably at least 0.63, further preferably at least 0.65, when excitedwith light having a peak wavelength of 400 nm or 455 nm.

(External quantum efficiency)=(internal quantum efficiency)×(absorptionefficiency)

(2-2-4) Preferred Combinations of the Respective Color-EmittingPhosphors

In the foregoing, the red emitting phosphor and the green emittingphosphor have been described. In Table 1, preferred combinations of theabove-described respective color-emitting phosphors are exemplified.

TABLE 1 Red emitting K₂TiF₆: Mn, BaTiF₆: Mn, K₂SiF₆: Mn, K₃ZrF₇: Mn,phosphors Ba_(0.65)Zr_(0.35)F_(2.7): Mn, K₂SnF₆: Mn, Na₂TiF₆: Mn,Na₂ZrF₆: Mn, K₂AlF₅: Mn, K₃AlF₆: Mn, K₃GaF₆: Mn, Zn₂AlF₇: Mn, KIn₂F₇: MnGreen emitting (Ba,Sr)₃Si₆O₁₂N₂: Eu, Eu-activated β SiAlON, phosphors(Ba,Sr,Ca,Mg)Si₂O₂N₂: Eu, (Ba,Sr,Ca,Mg)₂SiO₄: Eu, (Ba,Sr)MgAl₁₀O₁₇:Eu,Mn

Among the combinations shown in Table 1, more preferred combinations areshown in Table 2.

TABLE 2 Red emitting K₂TiF₆: Mn, BaTiF₆: Mn, K₂SiF₆: Mn phosphors Greenemitting (Ba,Sr)₃Si₆O₁₂N₂: Eu, Eu-activated β SiAlON, phosphors(Ba,Sr)MgAl₁₀O₁₇: Eu,Mn

Further, particularly preferred combinations are shown in Table 3.

TABLE 3 Red emitting K₂SiF₆: Mn phosphor Green emitting(Ba,Sr)₃Si₆O₁₂N₂: Eu, (Ba,Sr)MgAl₁₀O₁₇: Eu,Mn phosphors

The respective color emitting phosphors shown in the above Tables areexcited with light in a blue or deep blue region and emit light,respectively in narrow zones in the respective red and green regions,and they have excellent temperature characteristics such that there islittle change in their emission peak intensities due to a temperaturechange.

Accordingly, by combining two or more phosphors including the coloremitting phosphors with the solid light emitting device which emitslight in a blue or deep blue region, it is possible to obtain asemiconductor light emitting device which makes it possible to set theemission efficiency to be higher than ever and which is suitable for alight source to be used for a backlight for a color image display deviceof the present invention.

3. Light Emitting Device

The light emitting device of the present invention is not limited in itsconstruction except that the above-mentioned solid light emitting deviceand the above-mentioned green and red emitting phosphors are used andcan be obtained by adopting a known device construction by using knownphosphors such as a phosphor to emit a blue fluorescence (hereinaftersometimes referred to as “blue emitting phosphor”), a phosphor to emit agreen fluorescence (hereinafter sometimes referred to as “green emittingphosphor”), and a phosphor to emit a yellow fluorescence (hereinaftersometimes referred to as “yellow emitting phosphor”) as describedhereinafter in an optional combination in a blend ratio depending uponthe particular purpose.

Specific examples of the device construction will be describedhereinafter.

The emission spectrum of a light emitting device can be measured byusing, for example, a color/illuminance-measuring software made by OceanOptics, Inc and a USB2000 series spectrometer (integrating spherespecification) by conducting a current of 20 mA in a chamber maintainedat a temperature of 25±1° C. From such emission spectrum data in awavelength region of from 380 nm to 780 nm, the chromaticity values (x,y, z) can be calculated as chromaticity coordinates in the XYZ colorsystem stipulated in JIS Z8701. In such a case, a relational expressionof x+y+z=1 is established. In this specification, the above XYZ colorsystem may sometimes be referred to as an XY color system, which isusually represented by (x, y).

Further, with the light emitting device of the present invention, itsemission efficiency is usually at least 10 lm/W, preferably at least 30lm/W, particularly preferably at least 50 lm/W. Here, the emissionefficiency is obtained by obtaining a total luminous flux from theresults of an emission spectrum measurement using a light emittingdevice as described above, and dividing its lumen (lm) value by anelectric power consumption (W). The electric power consumption isdetermined as a product of a current value and a voltage value bymeasuring the voltage in a state where 20 mA is applied, by using e.g.True RMS Multimeters Model 187&189 manufactured by Fluke.

Here, white color of the white emitting device includes all of(yellowish) white, (greenish) white, (bluish) white, (purplish) white,as stipulated in JIS Z8701, and among them, preferred is white.

(3-1) Phosphors

The light emitting device of the present invention may optionallycontain, in addition to the above-described green and red emittingphosphors, the after-described second phosphors (such as a blue emittingphosphor, a green emitting phosphor, a yellow emitting phosphor and anorange emitting phosphor) depending upon its application, or theemission wavelength of the solid light emitting device as an excitationsource. Such phosphors may be used alone or as mixed in the form of aphosphor composition, as dispersed in a sealing material. Theweight-average median diameter of these phosphors to be used for a lightemitting device is usually at least 2 μm, preferably at least 5 μm andusually at most 30 μm, preferably at most 20 μm. If the weight-averagemedian diameter is too small, the luminance tends to be low, and thephosphor particles tend to aggregate. On the other hand, if theweight-average median diameter is too large, non-uniform coating orclogging of e.g. a dispenser tends to occur.

The composition of the second phosphors which are phosphors other thanthe phosphors of the present invention, is not particularly limited, butit may, for example, be one obtained by combining, as an activatedelement or co-activated element, ions of a rare earth metal such as Ce,Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm or Yb or ions of a metal such asAg, Cu, Au, Al, Mn or Sb, to host crystal of e.g. a metal oxiderepresented by e.g. Y₂ O₃, YVO₄, SnO₂, Y₂ SiO₅, Zn₂ SiO₄, Sr₂ SiO₄, Y₃Al₅ O₁₂, (Y,Gd)₃Al₅ O₁₂, YAlO₃, BaMgAl₁₀ O₁₇, (Ba,Sr)(Mg,Mn)Al₁₀ O₁₇,(Ba,Sr,Ca)(Mg,Zn,Mn)Al₁₀ O₁₇, BaAl₁₂ O₁₉, CeMgAl₁₁ O₁₉, (Ba,Sr,Mg)O.Al₂O₃, BaAl₂ Si₂ O₈, SrAl₂ O₄ or Sr₄ Al₁₄ O₂₅, a metal nitride representedby e.g. Sr₂ Si₅ N₈, a halophosphate such as Ca₁₀ (PO₄)₆ (F,Cl)₂ or(Sr,Ca,Ba,Mg)₁₀ (PO₄)₆ Cl₂, a phosphate represented by e.g. Sr₂ P₂ O₇ or(La,Ce)PO₄, a sulfide represented by e.g. ZnS, SrS, CaS, (Zn,Cd)S orSrGa₂ S₄, an oxysulfide represented by e.g. Y₂ O₂S or La₂ O₂ S or aborate such as GdMgB₅ O₁₀ or (Y,Gd)BO₃.

The above host crystal, activated element or coactivated element are notparticularly limited with respect to the element composition and maypartially be substituted by homologous elements. That is, the elementcomposition may be any composition so long as the obtainable phosphoremits visible light upon absorption of light in a near ultraviolet tovisible region.

Specifically, as such phosphors, ones given hereinafter may be employed,but they are merely exemplary, and phosphors which may be used in thepresent invention are by no means limited thereto. Further, in thefollowing examples, as mentioned above, phosphors different in only partof the structure are omitted as the case requires.

In the light emitting device of the present invention, in addition tothe above-described green emitting phosphor and red emitting phosphor,other types of green emitting phosphors and red emitting phosphors(homochromatic combination phosphors) may be used, as the case requires,depending upon the required properties.

(Orange or Red Emitting Phosphor)

As an orange or red emitting phosphor which may be combined with the redemitting phosphor of the present invention, an optional one may be usedso long as the effects of the present invention are not substantiallyimpaired.

At that time, the emission peak wavelength of the orange or red emittingphosphor as a homochromatic combination phosphor is usually at least 570nm, preferably at least 580 nm, more preferably at least 585 nm andusually at most 780 nm, preferably at most 700 nm, more preferably atmost 680 nm.

Such an orange or red emitting phosphor may, for example, be aneuropium-activated alkaline earth silicon nitride phosphor representedby (Mg,Ca,Sr,Ba)₂Si₅N₈:Eu which is composed of ruptured particles havinga red ruptured face and which emits light in a red region, or aneuropium-activated rare earth oxycarcogenide phosphor represented by(Y,La,Gd,Lu)₂O₂S:Eu which is composed of grown particles having asubstantially spherical shape as a regularly crystal-grown shape andwhich emits light in a red region.

Further, in the present invention, it is also possible to use phosphorsdisclosed in JP-A-2004-300247, which contain an oxynitride and/or anoxysulfide containing at least one element selected from the groupconsisting of Ti, Zr, Hf, Nb, Ta, W and Mo and which contains anoxynitride having a sialon structure wherein part or all of the Alelement is substituted by Ga element. Here, they are phosphorscontaining an oxynitride and/or an oxysulfide.

Further, as other red emitting phosphors, it is possible to use, forexample, an Eu-activated oxysulfide phosphor such as (La,Y)₂O₂S:Eu, anEu-activated oxide phosphor such as Y(V,P)O₄:Eu or Y₂O₃:Eu, anEu,Mn-activated silicate phosphor such as (Ba,Mg)₂SiO₄:Eu,Mn or(Ba,Sr,Ca,Mg)₂SiO₄:Eu,Mn, an Eu-activated tungstate phosphor such asLiW₂O₈:Eu, LiW₂O₈:Eu,Sm, Eu₂W₂O₉, Eu₂W₂O₉:Nb or Eu₂W₂O₉:Sm, anEu-activated sulfide phosphor such as (Ca,Sr)S:Eu, an Eu-activatedaluminate phosphor such as YAlO₃:Eu, an Eu-activated silicate phosphorsuch as Ca₂Y₈(SiO₄)₆O₂:Eu, LiY₉(SiO₄)₆O₂:Eu, (Sr,Ba,Ca)₃SiO₅:Eu orSr₂BaSiO₅:Eu, a Ce-activated aluminate phosphor such as (Y,Gd)₃Al₅O₁₂:Ceor (Tb,Gd)₃Al₅O₁₂:Ce, an Eu-activated oxide, nitride or oxynitridephosphor such as (Mg,Ca,Sr,Ba)₂Si₅(N,O)₈:Eu, (Mg,Ca,Sr,Ba)Si(N,O)₂:Eu or(Mg,Ca,Sr,Ba)AlSi(N,O)₃:Eu, a Ce-activated oxide, nitride or oxynitridephosphor such as (Mg,Ca,Sr,Ba)AlSi(N,O)₃:Ce, an Eu,Mn-activatedhalophosphate phosphor such as (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu,Mn, anEu,Mn-activated silicate phosphor such as Ba₃MgSi₂O₈:Eu,Mn or(Ba,Sr,Ca,Mg)₃(Zn,Mg)Si₂O₈:Eu,Mn, a Mn-activated germanate phosphor suchas 3.5MgO.0.5MgF₂.GeO₂:Mn, an Eu-activated oxynitride phosphor such asan Eu-activated a sialon, an Eu,Bi-activated oxide phosphor such as(Gd,Y,Lu,La)₂O₃:Eu,Bi, an Eu,Bi-activated oxisulfide phosphor such as(Gd,Y,Lu,La)₂O₂S:Eu,Bi, an Eu,Bi-activated vanadate phosphor such as(Gd,Y,Lu,La)VO₄:Eu,Bi, an Eu, Ce-activated sulfide phosphor such asSrY₂S₄:Eu,Ce, a Ce-activated sulfide phosphor such as CaLa₂S₄:Ce, anEu,Mn-activated phosphate phosphor such as (Ba,Sr,Ca)MgP₂O₇:Eu,Mn or(Sr,Ca,Ba,Mg,Zn)₂P₂O₇:Eu,Mn, an Eu,Mo-activated tungstate phosphor suchas (Y,Lu)₂WO₈:Eu,Mo, an Eu, Ce-activated nitride phosphor such as(Ba,Sr,Ca)_(x)Si_(y)N_(Z):Eu, Ce (wherein each of x, y and z is aninteger of at least 1), an Eu,Mn-activated halophosphate phosphor suchas (Ca,Sr,Ba,Mg)₁₀(PO₄)₆(F,Cl,Br,OH):Eu,Mn and a Ce-activated silicatephosphor such as (Y,Lu,Gd,Tb)_(1-x-y) Sc_(x) Ce_(y))₂ (Ca,Mg)_(1−r)(Mg,Zn)_(2+r) Si_(3−q) Ge_(q) O_(12+δ) (wherein each of x, y, r and δ isa number of 0 to 1, and q is a number of from 0 to 3).

As a red emitting phosphor, it is also possible to employ a red emittingorganic phosphor made of a rare earth element ion complex containing, asa ligand, an anion such as a β-diketonate, a β-diketone, an aromaticcarboxylic acid or a Broensted acid, a perylene pigment (such asdibenzo{[f,f′]-4,4′,7,T-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene),an anthraquinone pigment, a lake pigment, an azo pigment, a quinacridonepigment, an anthracene pigment, an isoindoline pigment, an isoindolinonepigment, a phthalocyanine pigment, a triphenylmethane basic dye, anindanthrone pigment, an indophenol pigment, a cyanine pigment or adioxadine pigment.

Especially, the red emitting phosphor preferably contains(Ca,Sr,Ba)₂Si₅(N,O)₈:Eu, (Ca,Sr,Ba)Si(N,O)₂:Eu, (Ca,Sr,Ba)AlSi(N,O)₃:Eu,(Ca,Sr,Ba)AlSi(N,O)₃:Ce, (Sr,Ba)₃SiO₅:Eu, (Ca,Sr)S:Eu, (La,Y)₂O₂S:Eu,(Ca,Sr,Ba)(Al,Ga)Si₄(N,O)₇:Eu or an Eu complex; more preferably itcontains (Ca,Sr,Ba)₂Si₅(N,O)₈:Eu, (Ca,Sr,Ba)Si(N,O)₂:Eu,(Ca,Sr,Ba)AlSi(N,O)₃:Eu, (Ca,Sr,Ba)AlSi(N,O)₃:Ce, (Sr,Ba)₃SiO₅:Eu,(Ca,Sr)S:Eu or (La,Y)₂O₂S:Eu, (Ca,Sr,Ba)(Al,Ga)Si₄(N,O)₇:Eu, or aβ-diketone type Eu complex or carboxylic acid type Eu complex such asEu(dibenzoylmethane)₃.1,10-phenanthroline complex; and particularlypreferably it is (Ca,Sr,Ba)₂Si₅(N,O)₈:Eu, (Sr, Ca)AlSiN₃:Eu,(Ca,Sr,Ba)(Al,Ga)Si₄(N,O)₇:Eu or (La,Y)₂O₂S:Eu.

Among the above, as an orange emitting phosphor, (Sr,Ba)₃ SiO₅:Eu ispreferred. particularly preferred is one or more red emitting phosphorsselected from the group consisting of (Sr, Ca)AlSiN₃:Eu and La₂O₂S:Eu.

(Green Emitting Phosphor)

As a green emitting phosphor which may be used in combination with thegreen emitting phosphor of the present invention, an optional one may beused so long as it does not substantially impair the effects of thepresent invention.

In a case where a green emitting phosphor is used as a second phosphor,as such a green emitting phosphor, any optional one may be used so longas it does not substantially impair the effects of the presentinvention. At that time, the emission peak wavelength of the greenemitting phosphor is usually more than 500 nm, preferably at least 510nm, more preferably at least 515 nm and usually at most 550 nm,preferably at most 542 nm, more preferably at most 535 nm. If thisemission peak wavelength is too short, the emission tends to be bluish.On the other hand, if it is too long, the emission tends to beyellowish. In either case, the characteristics as green light maydeteriorate.

Specifically, the green emitting phosphor may, for example, be aneuropium-activated alkaline earth silicone oxynitride phosphor(Mg,Ca,Sr,Ba)Si₂O₂N₂:Eu which is composed of ruptured particles having aruptured face and which emits light in a green region.

Further, as other green emitting phosphors, it is also possible to usean Eu-activated aluminate phosphor such as Sr₄Al₁₄O₂₅:Eu,(Ba,Sr,Ca)Al₂O₄:Eu, an Eu-activated silicate phosphor such as(Sr,Ba)Al₂Si₂O₈:Eu, (Ba,Mg)₂SiO₄:Eu, (Ba,Sr, Ca,Mg)₂SiO₄:Eu,(Ba,Sr,Ca)₂(Mg,Zn)Si₂O₇:Eu or (Ba,Ca,Sr,Mg)₉(Sc,Y,Lu,Gd)₂(Si,Ge)₆O₂₄:Eu,a Ce, Tb-activated silicate phosphor such as Y₂SiO₅:Ce, Tb, anEu-activated borophosphate phosphor such as Sr₂P₂O₇—Sr₂B₂O₅:Eu, anEu-activated halosilicate phosphor such as Sr₂Si₃O₈-2SrCl₂:Eu, aMn-activated silicate phosphor such as Zn₂SiO₄:Mn, a Tb-activatedaluminate phosphor such as CeMgAl₁₁O₁₉:Tb or Y₃Al₅O₁₂:Tb, a Tb-activatedsilicate phosphor such as Ca₂Y₈(SiO₄)₆O₂:Tb or La₃Ga₅SiO₁₄:Tb, an Eu,Tb, Sm-activated thiogallate such as (Sr,Ba,Ca)Ga₂S₄:Eu, Tb, Sm, aCe-activated aluminate phosphor such as (Y,Tb)₃(Al,Ga)₅O₁₂:Ce or(Y,Ga,Tb,La,Sm,Pr,Lu)₃(Al,Ga)₅O₁₂:Ce, a Ce-activated silicate phosphorsuch as Ca₃(Sc,Mg)₂Si₃O₁₂:Ce or Ca₃(Sc,Mg,Na,Li)₂Si₃O₁₂:Ce, aCe-activated oxide phosphor such as CaSc₂O₄:Ce, an Eu-activatedoxynitride phosphor such as Eu-activated β-sialon, an Eu,Mn-activatedaluminate phosphor such as (Ba,Sr)MgAl₁₀O₁₇:Eu,Mn, an Eu-activatedaluminate phosphor such as SrAl₂O₄:Eu, a Tb-activated oxysulfidephosphor such as (La,Gd,Y)₂O₂S:Tb, a Ce,Tb-activated phosphate phosphorsuch as LaPO₄:Ce,Tb, a sulfide phosphor such as ZnS:Cu,Al orZnS:Cu,Au,Al, a Ce,Tb-activated borate phosphor such as(Y,Ga,Lu,Sc,La)BO₃:Ce,Tb, Na₂Gd₂B₂O₇:Ce,Tb or (Ba,Sr)₂(Ca,Mg,Zn)B₂O₆:K,Ce,Tb, an Eu,Mn-activated halosilicate phosphor such asCa₈Mg(SiO₄)₄Cl₂:Eu,Mn, an Eu-activated thioaluminate phosphor orthiogallate phosphor such as (Sr,Ca,Ba)(Al,Ga,In)₂S₄:Eu, anEu,Mn-activated halosilicate phosphor such as(Ca,Sr)₈(Mg,Zn)(SiO₄)₄Cl₂:Eu,Mn, and an Eu-activated oxynitride phosphorsuch as M₃Si₆O₉N₄:Eu or M₃Si₆O₁₂N₂:Eu (wherein M is an alkaline earthmetal element).

Further, as a green emitting phosphor, it is also possible to employ anorganic phosphor such as a pyridine/phthaloimide condensationderivative, a benzooxadinone type, quinazorinone type, coumarin type,quinophthalone type or naphthalic acid imide type fluorescent colorant,or a terbium complex.

Among the above exemplified ones, as a green emitting phosphor, it ispreferred to use at least one member selected from the group consistingof (Ba,Sr, Ca,Mg)₂SiO₄:Eu, an Eu,Tb,Sm-activated thiogallate phosphorsuch as (Sr,Ba,Ca)Ga₂S₄:Eu,Tb,Sm, (Y,Tb)₃(Al,Ga)₅O₁₂:Ce, a Ce-activatedsilicate phosphor such as Ca₃(Sc,Mg)₂Si₃O₁₂:Ce orCa₃(Sc,Mg,Na,Li)₂Si₃O₁₂:Ce, a Ce-activated oxide phosphor such asCaSc₂O₄:Ce, an Eu-activated oxynitride phosphor such as Eu-activatedβ-sialon, an Eu,Mn-activated aluminate phosphor such as(Ba,Sr)MgAl₁₀O₁₇:Eu,Mn, an Eu-activated aluminate phosphor such asSrAl₂O₄:Eu, an Eu-activated thioaluminate phosphor or thiogallatephosphor such as (Sr,Ca,Ba)(Al,Ga,In)₂S₄:Eu, and an Eu-activatedoxynitride phosphor such as M₃Si₆O₁₂N₂:Eu (wherein M is an alkalineearth metal element). Further, among them, for a display application, itis preferred to use a phosphor having a narrow emission peak half-valuewidth. Specifically, it is preferred to use at least one member selectedfrom the group consisting of (Ba,Sr, Ca,Mg)₂SiO₄:Eu, an Eu-activatedthiogallate phosphor such as (Sr,Ba,Ca)Ga₂S₄:Eu, an Eu-activatedoxynitride phosphor such as Eu-activated β-sialon, an Eu,Mn-activatedaluminate phosphor such as (Ba,Sr)MgAl₁₀O₁₇:Eu,Mn, an Eu-activatedthioaluminate phosphor or thiogallate phosphor such as(Sr,Ca,Ba)(Al,Ga,In)₂S₄:Eu and an Eu-activated oxynitride phosphor suchas M₃Si₆O₁₂N₂:Eu (wherein M is an alkaline earth metal element); it ismore preferred to use (Ba,Sr)MgAl₁₀O₁₇:Eu,Mn; it is particularlypreferred to use BaMgAl₁₀O₁₇:Eu,Mn.

(Blue Emitting Phosphor)

In a case where a blue emitting phosphor is used for a light emittingdevice of the present invention, as such a blue emitting phosphor, anyoptional one may be used so long as it does not substantially impair theeffect of the present invention. At that time, the emission peakwavelength of the blue emitting phosphor is usually at least 420 nm,preferably at least 430 nm, more preferably at least 440 nm and usuallyat most 490 nm, preferably at most 480 nm, more preferably at most 470nm, further preferably at most 460 nm. When the emission peak wavelengthof the blue emitting phosphor to be used, is within this range, itoverlaps the excitation band of a red emitting phosphor to be used inthe present invention, and by the blue light from the blue emittingphosphor, the red emitting phosphor to be used in the present inventioncan be efficiently excited.

Such a blue emitting phosphor may, for example, be an europium-activatedbarium magnesium aluminate phosphor represented by(Ba,Sr,Ca)MgAl₁₀O₁₇:Eu which is composed of grown particles having asubstantially hexagonal shape as a regular crystal growth shape andwhich emits light in a blue region, an europium-activated halophosphatecalcium phosphor represented by (Mg,Ca,Sr,Ba)₅(PO₄)₃(Cl,F):Eu which iscomposed of grown particles having a substantially spherical shape as aregular crystal growth shape and which emits light in a blue region, aneuropium-activated alkaline earth chloroborate phosphor represented by(Ca,Sr,Ba)₂B₅O₉Cl:Eu which is composed of grown particles havingsubstantially a cubic shape as a regular crystal growth shape and whichemits light in a blue region, or an europium-activated alkaline earthaluminate phosphor represented by (Sr,Ca,Ba)Al₂O₄:Eu or(Sr,Ca,Ba)₄Al₁₄O₂₅:Eu which is composed of ruptured particles having aruptured face and which emits light in a bluish green region.

Further, as a blue emitting phosphor, it is also possible to use aSn-activated phosphate phosphor such as Sr₂P₂O₇:Sn, an Eu-activatedaluminate phosphor such as (Sr,Ca,Ba)Al₂O₄:Eu, (Sr,Ca,Ba)₄Al₁₄O₂₅:Eu,BaMgAl₁₀O₁₇:Eu, (Ba,Sr,Ca)MgAl₁₀O₁₇:Eu, BaMgAl₁₀O₁₇:Eu,Tb,Sm orBaAl₈O₁₃:Eu, a Ce-activated thiogallate phosphor such as SrGa₂S₄:Ce orCaGa₂S₄:Ce, an Eu,Mn-activated aluminate phosphor such as(Ba,Sr,Ca)MgAl₁₀O₁₇:Eu,Mn, an Eu-activated halophosphoate phosphor suchas (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu or(Ba,Sr,Ca)₅(PO₄)₃(Cl,F,Br,OH):Eu,Mn,Sb, an Eu-activated silicatephosphor such as BaAl₂Si₂O₈:Eu or (Sr,Ba)₃MgSi₂O₈:Eu, an Eu-activatedphosphate phosphor such as Sr₂P₂O₇:Eu, a sulfide phosphor such as ZnS:Agor ZnS:Ag,Al, a Ce-activated silicate phosphor such as Y₂SiO₅:Ce, atungstate phosphor such as CaWO₄, an Eu,Mn-activated borophosphatephosphor such as (Ba,Sr,Ca)BPO₅:Eu,Mn, (Sr,Ca)₁₀(PO₄)₆.nB₂O₃:Eu or2SrO.0.84P₂O₅.0.16B₂O₃:Eu, an Eu-activated halosilicate phosphor such asSr₂Si₃O₈.2SrCl₂:Eu, an Eu-activated oxynitride phosphor such asSrSi₉Al₁₉ON₃₁:Eu or EuSi₉Al₁₉ON₃₁, or a Ce-activated oxynitride phosphorsuch as La_(1-x) Ce_(x)Al(Si_(6-z)Al_(z))(N_(10-z)O_(z)) (wherein x andy are, respectively, numbers satisfying 0≦x≦1 and 0≦z≦6), or La_(1-x-y)Ce_(x) Ca_(y) Al(Si_(6-z)Al_(z))(N_(10-z)O_(z)) (wherein x, y and z are,respectively, numbers satisfying 0≦x≦1, 0≦y≦1 and 0≦z≦6).

Further, as a blue emitting phosphor, it is also possible to employ, forexample, an organic phosphor such as a fluorescent colorant of anaphthalic acid imide type, benzooxazole type, styryl type, coumarintype, pyrazoline type or triazole type compound, or thulium complex.

Among the above exemplified ones, as a blue emitting phosphor, itpreferably contains (Ca,Sr,Ba)MgAl₁₀O₁₇:Eu,(Sr,Ca,Ba,Mg)₁₀(PO₄)₆(Cl,F)₂:Eu or (Ba,Ca,Mg,Sr)₂SiO₄:Eu; it morepreferably contains (Ca,Sr,Ba)MgAl₁₀O₁₇:Eu,(Sr,Ca,Ba,Mg)₁₀(PO₄)₆(Cl,F)₂:Eu or (Ba,Ca,Sr)₃MgSi₂O₈:Eu; and it furtherpreferably contains BaMgAl₁₀O₁₇:Eu, Sr₁₀(PO₄)₆(Cl,F)₂:Eu orBa₃MgSi₂O₈:Eu. Further, among them, for a display application,(Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu or (Ca,Sr,Ba)MgAl₁₀O₁₇:Eu having a narrowemission peak half-value width is preferred; (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Euis more preferred; and Sr₁₀(PO₄)₆Cl₂:Eu is particularly preferred.

Among the above-mentioned ones, a phosphor represented by(Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu is preferably one obtained by a multistagefiring process as described in the after-described Preparation ExampleI-7 wherein a flux is used in the second or subsequent firing step. Assuch a phosphor, one disclosed in WO2009/005035 may be mentioned.

Further, as a phosphor represented by (Ca,Sr,Ba)MgAl₁₀O₁₇:Eu, a phosphoris preferred which contains an alkali metal in the crystal phase of thephosphor and wherein the content of the alkali metal element is at most3% based on the number of sites which can be substituted by Eu, since ithas a constantly high emission intensity and luminance even underexcitation with a near ultraviolet light and it is excellent also in thetemperature characteristics.

Further, as such a phosphor, one containing F as an anionic element ispreferred.

The type and content of the above alkali metal element and the contentof the F element are the same as those described above with respect tothe formula (G7). Such a phosphor can be prepared as disclosed inWO2008/123498 by permitting a monovalent metal halide to be present as aflux in a prescribed concentration during the firing of the raw materialmixture.

As such a blue emitting phosphor, it is particularly preferred to employone, of which the variation rate of the emission peak intensity at 100°C. to the emission intensity at 25° C., when the wavelength of theexcitation light is 400 nm or 405 nm, is at most 30%, more preferably atmost 25%, further preferably at most 22%, still further preferably atmost 18%, particularly preferably at most 15%.

In the light emitting device of the present invention, the green and redemitting phosphors excellent in the temperature dependency are used, andtherefore, it is preferred that also the blue emitting phosphor has suchcharacteristics, whereby a color shift can be prevented.

Here, the temperature dependency of the blue emitting phosphor can bemeasured in the same manner as the measurement of the temperaturedependency of the above-described green and red emitting phosphorsexcept that the wavelength of the excitation light is adjusted to 400 nmor 405 nm.

Any one of the above exemplified blue emitting phosphors may be usedalone, or two or more of them may be used in an optional combination orratio.

(Yellow Emitting Phosphor)

In a case where a yellow emitting phosphor is used for a light emittingdevice of the present invention, as such a yellow emitting phosphor, anyoptional one may be used so long as it does not substantially impair theeffects of the present invention. At that time, the emission peakwavelength of the yellow emitting phosphor is usually at least 530 nm,preferably at least 540 nm, more preferably at least 550 nm and usuallyat most 620 nm, preferably at most 600 nm, more preferably at most 580nm.

As such a yellow phosphor, various phosphors of oxide type, nitridetype, oxynitride type, sulfide type, oxysulfide type, etc., may bementioned. Particularly, it may be a garnet phosphor having a garnetstructure represented by e.g. RE₃M₅O₁₂:Ce (wherein R_(E) is at least oneelement selected from the group consisting of Y, Tb, Gd, Lu, and Sm, andM is at least one element selected from the group consisting of Al, Gaand Sc) or M^(a) ₃M^(b) ₂M^(c) ₃O₁₂:Ce (wherein M^(a) is a bivalentmetal element, M^(b) is a trivalent metal element, and M^(c) is atetravalent metal element), an orthosilicate phosphor represented byAE₂M^(d)O₄:Eu (wherein AE is at least one element selected from thegroup consisting of Ba, Sr, Ca, Mg and Zn, and M^(d) is Si and/or Ge),an oxynitride phosphor having part of oxygen as a constituting elementof such a phosphor substituted by nitrogen, or a Ce-activated phosphorof e.g. a nitride phosphor having a CaAlSiN₃ structure, such asAEAlSiN₃:Ce (wherein AE is at least one element selected from the groupconsisting of Ba, Sr, Ca, Mg and Zn).

Further, as a yellow emitting phosphor, it is also possible to employ asulfide phosphor such as CaGa₂S₄:Eu, (Ca,Sr)Ga₂S₄:Eu or(Ca,Sr)(Ga,Al)₂S₄:Eu, an Eu-activated phosphor such as an oxynitfidetype phosphor having a sialon structure such asCa_(x)(Si,Al)₁₂(O,N)₁₆:Eu (wherein x is 0<x≦4), an Eu-activated orEu,Mn-coactivated halogenated borate phosphor such as (M_(1-A-B) EU_(A)Mn_(B))₂ (BO₃)_(1-P) (PO₄)_(P) X (wherein M is at least one elementselected from the group consisting of Ca, Sr and Ba, X is at least oneelement selected from the group consisting of F, Cl and Br, and A, B andP are respectively numbers satisfying 0.001≦A≦0.3, 0≦B≦0.3 and 0≦P≦0.2),or a Ce-activated nitride phosphor having a La₃ Si₆ N₁₁ structure whichmay contain an alkaline earth metal element.

Further, as a yellow emitting phosphor, it is possible to employ, forexample, a fluorescent dye such as brilliant sulfoflavine FF (ColourIndex Number 56205), basic yellow HG (Colour Index Number 46040), eosine(Colour Index Number 45380) or rhodamine 6G (Colour Index Number 45160).

Any one of the above exemplified yellow emitting phosphors may be usedalone, or two or more of them may be used in an optional combination orratio.

(3-1-1) Combination of Phosphors

The amounts of the above-mentioned respective phosphors, and thecombination, the ratio, etc. of the phosphors may optionally be setdepending upon e.g. the particular application of the light emittingdevice.

For example, in a case where the light emitting device of the presentinvention is to be constructed as a red emitting device, only the redemitting phosphor of the present invention may be used, and use of otherphosphors is usually unnecessary.

On the other hand, in a case where the light emitting device of thepresent invention is to be constructed as a white emitting device, thered emitting phosphor and green emitting phosphor are used, and, as thecase requires, a blue emitting phosphor and/or a yellow emittingphosphor may, for example, be suitably combined, in order to obtain thedesired white light. Specifically, the following combination (A) or (B)may be mentioned as a preferred combination of phosphors in a case wherethe light emitting device of the present invention is constructed as awhite emitting device.

(A) As the first illuminant, a blue illuminant (blue emitting LED or thelike) is used, and the above-described red emitting phosphor and one ormore green emitting phosphors selected from the group consisting of a(Ba,Sr,Ca,Mg)₂SiO₄:Eu type phosphor, a (Ca,Sr)Sc₂O₄:Ce type phosphor, a(Ca₃(Sc,Mg)₂Si₃O₁₂:Ce type phosphor, an Eu-activated β-sialon typephosphor, a (Mg,Ca,Sr,Ba)Si₂O₂N₂:Eu type phosphor and a(Mg,Ca,Sr,Ba)₃Si₆O₁₂N₂:Eu type phosphor, are used.

(B) As a first illuminant, a near ultraviolet or violet illuminant (nearultraviolet or violet emitting LED or the like) is used, the above redemitting phosphor and one or more green emitting phosphor are used, anda blue emitting phosphor is further used in combination. In this case,as the blue emitting phosphor, a (Ba,Sr)MgAl₁₀O₁₇:Eu type phosphorand/or a (Sr,Ca,Ba,Mg)₁₀(PO₄)₆(Cl,F)₂:Eu type phosphor is used, and asthe green emitting phosphor, one or more green emitting phosphorsselected from the group consisting of a (Ba,Sr)MgAl₁₀O₁₇:Eu,Mn typephosphor, a (Ba,Sr,Ca,Mg)₂SiO₄:Eu type phosphor, a (Ca,Sr)Sc₂O₄:Ce typephosphor, a Ca₃(Sc,Mg)₂Si₃O₁₂:Ce type phosphor, an Eu-activated β-sialontype phosphor, a (Mg,Ca,Sr,Ba)Si₂O₂N₂:Eu type phosphor, a(Mg,Ca,Sr,Ba)₃Si₆O₁₂N₂:Eu type phosphor, a (Ba,Sr,Ca)₄Al₁₄O₂₅:Eu and(Ba,Sr,Ca)Al₂O₄:Eu type phosphors, are used.

It is particularly preferred to use a phosphor having a narrow emissionpeak half-value width for each of three colors of red, blue and green,since it is thereby possible to remarkably improve the colorreproduction range of a display. Specifically, it is preferred to use anear ultraviolet emitting LED, the red emitting phosphor of the presentinvention, (Ba,Sr)MgAl₁₀O₁₇:Eu,Mn as a green emitting phosphor and(Sr,Ca,Ba,Mg)₁₀(PO₄)₆(Cl,F)₂:Eu as a blue emitting phosphor, incombination.

Now, depending upon the applications of the light emitting device,suitable combinations of the solid light emitting device and thephosphors are shown in Tables 4 to 8 and will be described in furtherdetail.

TABLE 4 (1) CASES WHERE BLUE ILLUMINANT IS USED AS FIRST ILLUMINANTFirst illuminant Green emitting phosphor Red emitting phosphor (1-1)APPLICATION OF IMAGE DISPLAY DEVICE TO BACKLIGHT Blue emitting(Mg,Ca,Sr,Ba)Si₂O₂N₂: Eu Red emitting phosphor LED (Ba,Sr,Ca,Mg)₂SiO₄:Eu of the invention (Ba,Sr)₃Si₆O₁₂N₂: Eu Eu-activated β-sialon (1-2)APPLICATION TO ILLUMINATING DEVICE Blue emitting (Y,Tb)₃(Al,Ga)₅O₁₂: CeRed emitting phosphor LED Ca₃(Sc,Mg,Na,Li)₂Si₃O₁₂: Ce of the invention(Ca,Sr)Sc₂O₄: Ce (Mg,Ca,Sr,Ba)Si₂O₂N₂: Eu (Ba,Sr,Ca,Mg)₂SiO₄: Eu(Ba,Sr)₃Si₆O₁₂N₂: Eu

TABLE 5 (2) CASES WHERE NEAR ULTRAVIOLET ILLUMINANT IS USED AS FIRSTILLUMINANT First illuminant Blue emitting phosphor Green emittingphosphor Red emitting phosphor (2-1) APPLICATION OF IMAGE DISPLAY DEVICETO BACKLIGHT Near ultraviolet (Sr,Ca,Ba,Mg)₁₀(PO₄)₆(Cl,F)₂: Eu(Mg,Ca,Sr,Ba)Si₂O₂N₂: Eu Red emitting phosphor emitting LED(Sr,Ba)₃MgSi₂O₈: Eu (Ba,Sr,Ca,Mg)₂SiO₄: Eu of the invention(Ba,Sr,Ca)MgAl₁₀O₁₇: Eu (Ba,Sr)₃Si₆O₁₂N₂: Eu Eu-activated β-sialon(Ba,Sr)MgAl₁₀0₁₇: Eu,Mn (2-2) APPLICATION TO ILLUMINATING DEVICE Nearultraviolet (Sr,Ca,Ba,Mg)₁₀(PO₄)₆(Cl,F)₂: Eu (Y,Tb)₃(Al,Ga)₅O₁₂: Ce Redemitting phosphor emitting LED (Sr,Ba)₃MgSi₂O₈: EuCa₃(Sc,Mg,Na,Li)₂Si₃O₁₂: Ce of the invention (Ba,Sr,Ca)MgAl₁₀O₁₇: Eu(Ca,Sr)Sc₂O₄: Ce (Mg,Ca,Sr,Ba)Si₂O₂N₂: Eu (Ba,Sr,Ca,Mg)₂SiO₄: Eu(Ba,Sr)₃Si₆O₁₂N₂: Eu (Sr,Ca,Ba)Al₂O₄: Eu

Further, among them, the following combinations are further preferred.

TABLE 6 (1) CASES WHERE BLUE ILLUMINANT IS USED AS FIRST ILLUMINANTFirst illuminant Green emitting phosphor Red emitting phosphor (1-1)APPLICATION OF IMAGE DISPLAY DEVICE TO BACKLIGHT Blue emitting(Mg,Ca,Sr,Ba)Si₂O₂N₂: Eu Red emitting phosphor LED (Ba,Sr,Ca,Mg)₂SiO₄:Eu of the invention (Ba,Sr)₃Si₆O₁₂N₂: Eu Eu-activated β-sialon (1-2)APPLICATION TO ILLUMINATING DEVICE Blue emitting Y₃(Al,Ga)₅O₁₂: Ce Redemitting phosphor LED Ca₃(Sc,Mg)₂Si₃O₁₂: Ce of the invention CaSc₂O₄: Ce(Sr,Ba)Si₂O₂N₂: Eu (Ba,Sr,Ca)₂SiO₄: Eu (Ba,Sr)₃Si₆O₁₂N₂: Eu

TABLE 7 (2) CASES WHERE NEAR ULTRAVIOLET ILLUMINANT IS USED AS FIRSTILLUMINANT First illuminant Blue emitting phosphor Green emittingphosphor Red emitting phosphor (2-1) APPLICATION OF IMAGE DISPLAY DEVICETO BACKLIGHT Near ultraviolet Sr₁₀(PO₄)₆Cl₂: Eu (Sr,Ba)Si₂O₂N₂: Eu Redemitting phosphor emitting LED (Sr,Ba)₃MgSi₂O₈: Eu (Ba,Sr)₂SiO₄: Eu ofthe invention BaMgAl₁₀O₁₇: Eu (Ba,Sr)₃Si₆O₁₂N₂: Eu Eu-activated β-sialonBaMgAl₁₀O₁₇: Eu,Mn (2-2) APPLICATION TO ILLUMINATING DEVICE Nearultraviolet Sr₁₀(PO₄)₆Cl₂: Eu Y₃(Al,Ga)₅O₁₂: Ce Red emitting phosphoremitting LED (Sr,Ba)₃MgSi₂O₈: Eu Ca₃(Sc,Mg)₂Si₃O₁₂: Ce of the inventionBaMgAl₁₀O₁₇: Eu CaSc₂O₄: Ce (Sr,Ba)Si₂O₂N₂: Eu (Ba,Sr,Ca)₂SiO₄: Eu(Ba,Sr)₃Si₆O₁₂N₂: Eu (Sr,Ca,Ba)Al₂O₄: Eu

Among them, the following combinations are further preferred.

TABLE 8 (1) CASES WHERE BLUE ILLUMINANT IS USED AS FIRST ILLUMINANTFirst illuminant Green emitting phosphor Red emitting phosphor (1-1)APPLICATION OF IMAGE DISPLAY DEVICE TO BACKLIGHT Blue emitting(Ba,Sr)₂SiO₄: Eu Red emitting phosphor LED (Ba,Sr)₃Si₆O₁₂N₂: Eu of theinvention Eu-activated β-sialon (1-2) APPLICATION TO ILLUMINATING DEVICEBlue emitting Y₃(Al,Ga)₅O₁₂: Ce Red emitting phosphor LEDCa₃(Sc,Mg)₂Si₃O₁₂: Ce of the invention CaSc₂O₄: Ce (2) CASES WHERE NEARULTRAVIOLET ILLUMINANT IS USED AS FIRST ILLUMINANT First illuminant Blueemitting phosphor Green emitting phosphor Red emitting phosphor (2-1)APPLICATION OF IMAGE DISPLAY DEVICE TO BACKLIGHT Near ultravioletSr₁₀(PO₄)₆Cl₂: Eu BaMgAl₁₀O₁₇: Eu,Mn Red emitting phosphor emitting LEDof the invention (2-2) APPLICATION TO ILLUMINATING DEVICE Nearultraviolet BaMgAl₁₀O₁₇: Eu (Ba,Sr,Ca)₂SiO₄: Eu Red emitting phosphoremitting LED (Ba,Sr)₃Si₆O₁₂N₂: Eu of the invention

(3-2) Construction of Light Emitting Device (Phosphor-ContainingComposition)

In the light emitting device of the present invention, theabove-described phosphors are used usually in the state of aphosphor-containing composition having them dispersed in a liquid mediumas a sealing material (binder). One having the phosphors of the presentinvention dispersed in a liquid medium will be referred to as “thephosphor-containing composition of the present invention”, as the caserequires.

(3-2-1) Liquid Medium

The liquid medium to be used for the phosphor-containing composition ofthe present invention is not particularly limited so long as it does notimpair the performance of the phosphors within the desired range, butusually, a curable material which can be molded to cover the solid lightemitting device, may be employed.

The curable material is a material which is a fluid material and can becured by applying certain curing treatment. Here, “fluid” means, forexample, a liquid or gel state. The curable material is not limited withrespect to the specific type, so long as it reserves a role of guidinglight emitted from the solid light emitting device to the phosphors.Further, one of curable materials may be used alone, or two or more ofthem may be used in an optional combination or ratio.

Accordingly, the curable material may be any material so long as itshows a liquid nature under the desired working conditions and it iscapable of well dispersing the phosphors of the present invention and atthe same time will not bring about an undesirable reaction, and aninorganic material, an organic material or a mixture of both may beemployed.

An inorganic material may, for example, be a metal alkoxide; a solutionobtained by hydrolyzing and polymerizing a solution containing a ceramicprecursor polymer or a metal alkoxide by a sol-gel method; or aninorganic material having such a combination solidified (e.g. aninorganic material having siloxane bonds).

On the other hand, an organic material may, for example, be athermoplastic resin, a thermosetting resin or a photocurable resin.Specific examples include, for example, a (meth)acrylic resin such aspolymethyl (meth)acrylate; a styrene resin such as polystyrene or astyrene/acrylonitrile copolymer; a polycarbonate resin; a polyesterresin; a phenoxy resin; a butyral resin; a polyvinyl alcohol; acellulose resin such as ethyl cellulose, cellulose acetate or celluloseacetate butyrate; an epoxy resin; a phenol resin; and a silicone resin.

Among the above inorganic materials and organic materials, it isparticularly preferred to use a silicon-containing compound which isexcellent in heat resistance and which is substantially free fromdeterioration by light emitted from a light emitting device.

A silicon-containing compound is a compound having silicon atoms in itsmolecule, and it may be an organic material (a silicone compound) suchas a polyorganosiloxane, an inorganic material such as silicon oxide,silicon nitride or silicon oxynitride, or a glass material such as aborosilicate, a phosphosilicate or an alkali metal silicate. Among them,a silicone material is preferred since it is excellent in transparency,adhesion, handling efficiency, mechanical and thermal relaxationproperties.

Such a silicone material usually means an organic polymer having asiloxane bond as the main chain, and, for example, a silicone materialof e.g. condensation type, addition type, improved sol-gel type orphotocurable type may be used.

As a condensation type silicone material, for example, components forsemiconductor light emitting devices disclosed in e.g. JP-A-2007-112973to 112975, JP-A-2007-19459 and JP-A-2008-34833, may be used. Such acondensation type silicone material is excellent in adhesion with acomponent such as a package, an electrode or a light emitting element tobe used for a semiconductor light emitting device, whereby addition ofan adhesion-improving component can be minimized, and crosslinking ismainly by siloxane bonds, whereby there is a merit in that it isexcellent in heat resistance and light resistance.

As an addition type silicone material, it is possible to suitably use,for example, a silicone material for potting as disclosed in e.g.JP-A-2004-186168, JP-A-2004-221308 and JP-A-2005-327777, an organicmodified silicone material for potting as disclosed in e.g.JP-A-2003-183881 and JP-A-2006-206919, a silicone material for injectionmolding as disclosed in e.g. JP-A-2006-324596 or a silicone material fortransfer molding as disclosed in e.g. JP-A-2007-231173. Such an additiontype silicone material has merits such that the degree of freedom ishigh in selection of e.g. the curing rate or the hardness of the curedproduct, it is free from a component which detaches at the time ofcuring and substantially free from curing shrinkage, and it is excellentin depth curability.

Further, as an improved sol-gel type silicone material as one of thecondensation type silicone material, it is possible to suitably use, forexample, a silicone material as disclosed in e.g. JP-A-2006-077234,JP-A-2006-291018 and JP-A-2007-119569. Such an improved sol-gel typesilicone material has merits such that it has a high crosslinking degreeand is excellent in durability with high heat resistance and lightresistance and it has low gas permeability and is excellent also in thefunction to protect a phosphor having low moisture resistance.

As a photocurable type silicone material, it is possible to suitably usea silicone material as disclosed in e.g. JP-A-2007-131812 andJP-A-2007-214543. An ultraviolet curable type silicone material hasmerits such that it cures in a short time and thus is excellent inproductivity, and it is not required to apply a high temperature forcuring, whereby deterioration of the light emitting device is lesslikely to take place.

Such a silicone material may be used alone, or a plurality of suchsilicone materials may be used as mixed, if no curing inhibition takesplace by such mixing.

Especially in a case where it is used for a semiconductor light emittingdevice, it is more preferred to use a condensation type siliconematerial from the viewpoint of the heat resistance and deteriorationresistance against the emission wavelengths in an ultraviolet region toa blue region.

(3-2-2) Contents of Liquid Medium and Phosphors

The content of the liquid medium is optional so long as the effects ofthe present invention are not substantially impaired, but it is usuallyat least 25 wt %, preferably at least 40 wt % and usually at most 99 wt%, preferably at most 95 wt %, more preferably at most 80 wt %, based onthe entire phosphor-containing composition of the present invention.There will be no particular problem in a case where the amount of theliquid medium is large. However, in order to obtain the desiredchromaticity coordinates, color rendering index, emission efficiency,etc. when made into a semiconductor light emitting device, it is usuallyadvisable to use the liquid medium in the above-mentioned content. Onthe other hand, if the liquid medium is too small, the fluiditydeteriorates, whereby the handling tends to be difficult.

In the phosphor-containing composition of the present invention, theliquid medium has a role mainly as a binder. One type of such a liquidmedium may be used alone, or two or more types may be used in anoptional combination or ratio. For example, in a case where asilicon-containing compound is used for the purpose of improving e.g.heat resistance or light resistance another heat curable resin such asan epoxy resin may be contained within a range not to impair thedurability of the silicon-containing compound. In such a case, thecontent of another heat curable resin is usually at most 25 wt %,preferably at most 10 wt %, based on the total amount of the liquidmedium as the binder.

The content of the phosphors in the phosphor-containing composition ofthe present invention is optional so long as the effects of the presentinvention are not substantially impaired, but it is usually at least 1wt %, preferably at least 3 wt %, more preferably at least 5 wt %,further preferably at least 10 wt %, particularly preferably at least 20wt % and usually at most 80 wt %, preferably at most 60 wt %, based onthe entire phosphor-containing composition of the present invention.Further, the proportion of the phosphors of the present inventionoccupying the phosphors in the phosphor-containing composition is alsooptional, but it is usually at least 30 wt %, preferably at least 50 wt% and usually at most 100 wt %. If the content of the phosphors in thephosphor-containing composition is too much, the fluidity of thephosphor-containing composition tends to be poor, and handling tends tobe difficult, and if the content of the phosphors is too small, theemission efficiency of the light emitting device tends to be low.

(3-2-3) Other Components

Further, in the liquid medium, additives such as a diffusing agent tomake the emission light to be more uniform, a filler, aviscosity-controlling agent, an ultraviolet absorber, a refractiveindex-controlling agent, a shrinkage-reducing agent and a binder may becontained as other components, so long as they do not substantiallyimpair the effects of the present invention. One type of such othercomponents may be used alone, or two or more types may be used in anoptional combination or ratio.

As the diffusing agent, a colorless material having a size of from 100nm to a few tens μm by an average particle size, is preferred. Alumina,zirconia, yttoria or the like can be preferably employed as thediffusing agent, since it is stable in a practical temperature range offrom −60 to 120° C. Further, if the refractive index is high, theeffects of the diffusing agent will be high, such being more preferred.

Further, in a case where phosphors having large particle sizes are used,color shading or color shift is likely to occur due to precipitation ofthe phosphors, and accordingly, it is preferred to incorporate aprecipitation preventing agent to the binder. As theprecipitation-preventing agent, ultrafine particulate silica having aparticle size of about 10 nm or fumed silica (dried silica), such as“tradename: AEROSIL #200, manufactured by Nippon Aerosil Co., Ltd.” or“tradename: Reolosil, manufactured by Tokuyama Corporation” is common.

(3-3) Construction of Light Emitting Device (Others)

So long as the light emitting device of the present invention isprovided with the above-described solid light emitting device andphosphors, other constructions are not particularly limited. Usually,however, the above-described solid light emitting device and phosphorsare disposed on a suitable frame. At that time, they are disposed sothat the phosphors are excited by light emitted from the solid lightemitting device to emit light, and the emission of the solid lightemitting device and/or the emission of the phosphors is taken out to theexterior. In such a case, a plurality of phosphors may not necessarilybe mixed in the same layer. For example, phosphors may be contained inseparate layers for the respective emission colors of the phosphors, andsuch layers may be deposited.

The above frame has at least positive and negative electrodes to conductcurrent to the light source of the solid light emitting device, and theelectrodes of the solid light emitting device and the electrodes of theframe are electrically connected. These electrodes are electricallyconnected by wire bonding or flip chip bonding. When they are bonded bywire bonding, a gold wire or aluminum wire having a diameter of from 20to 40 μm may be employed.

The light emitting device of the present invention can be made to be alight emitting device suitable for a light source for theafter-mentioned backlight for an image display device by combining aspecific red emitting phosphor and a specific green emitting phosphor tobe excited by an emission having wavelengths in an ultraviolet to blueregion and by combining them with another specific blue emittingphosphor, as the case requires. That is, the red emitting phosphor to beused in the present invention presents luminance which has a narrow bandin a red region and is excellent in the temperature characteristics, andaccordingly, by combining it with the above solid light emitting deviceand phosphors, it is possible to produce a semiconductor light emittingdevice as a light source for a backlight for an image display devicewhich is capable of setting the emission efficiency at a level higherthan ever and yet is capable of setting the color reproduction rangebroader than ever.

Further, in an application to a light source for a backlight for animage display device employing a plurality of solid light emittingdevices, it is desired to use, as such solid light emitting devices,ones having little fluctuation in the emission efficiency. Sincephosphors to be excited by wavelengths in a near ultraviolet to blueregion are, in many cases, ones, of which the excitation efficiencysubstantially changes in the vicinity of a wavelength of 400 nm, it isparticularly preferred to use a semiconductor light emitting devicehaving little fluctuation in the emission efficiency. Specifically, thedegree of fluctuation in the emission wavelength at which the emissionefficiency in a semiconductor light emitting device becomes maximum, isusually at most ±5 nm, preferably at most ±2.5 nm, more preferably atmost ±1.25 nm.

Further, a concave cup is provided on the frame, and the solid lightemitting device is disposed on its bottom surface, whereby it ispossible to let the outgoing light have directivity and thereby toeffectively utilize the light. Further, by subjecting the inner surfaceof the concave portion or the entirety of the frame to plating treatmentwith a highly reflective metal such as silver, platinum or aluminum orits alloy, it is possible to increase the reflectance in the entirevisible light region and thereby to increase the light use efficiency,such being more preferred. Further, similar effects can be obtained bymaking the surface of the concave portion or the entirety of the framefrom an injection molding resin containing a highly reflective materialsuch as a white-colored glass fiber, alumina powder or titania powder.

To fix the solid light emitting device, an adhesive of e.g. epoxy type,imide type or acrylic type, a solder of AuSn or AgSn, or bumps of e.g.Au may, for example, be used.

In a case where the solid light emitting device is electricallyconnected through the adhesive, an electrically conductive filler suchas fine silver particles may be incorporated to the adhesive, or, forexample, a silver paste or carbon paste may be applied thinly anduniformly thereon. Further, in the case of a light emitting diode orlaser diode of a large current type where the heat dissipation becomesimportant, solder is effective. In a case where the solid light emittingdevice is not electrically connected through the adhesive, any adhesivemay be used for fixing the light source, but in consideration of theheat dissipation, a silver paste or solder is preferred.

In a case where a plurality of solid light emitting devices areemployed, use of a solder is not advisable, since the solid lightemitting devices are likely to be repeatedly exposed at high temperatureor so exposed for a long time, whereby the useful life of the solidlight emitting devices may be deteriorated. On the other hand, whenbumps are used, the operation can be carried out at a temperature lowerthan the solder, and bonding can be carried out simply and certainly.Especially in a case where a flip chip type LED is to be used, a silverpaste adhesive may short-circuit the p-type and n-type electrodes, butthe bumps are free from such a trouble and thus are preferred.

In the light emitting device of the present invention, in addition tothe above-described solid light emitting device, phosphors and frame,other components may be employed. Further, the solid light emittingdevice is preferably sealed by a sealing material. As such a sealingmaterial, the above-described phosphor-containing composition may servealso as a sealing material, or the above-described liquid medium may beused as a sealing material. Such a sealing material may be used not onlyfor the purpose of dispersing phosphors in a light emitting device, butalso for the purpose of bonding the solid light emitting device, thephosphors and the frame.

When the light emitting device of the present invention is switched on,firstly the solid light emitting device will emit light in a blue todeep blue region or in an ultraviolet region. The phosphor will absorb apart of the emission and will emit a green or red color. As the lightcoming out from the light emitting device, in a case where the solidlight emitting device emits a blue color, the blue light of the solidlight emitting device will be mixed with the green and red lights havingwavelengths changed by the phosphors thereby to present substantiallywhite color. Whereas, in a case where the solid light emitting deviceemits light in a deep blue region or in an ultraviolet region, lights ofblue, green and red colors having wavelengths changed directly orindirectly by the phosphors from the light in the deep blue region or inthe ultraviolet region emitted from the solid light emitting device,will be mixed to present substantially white light.

(3-4) Practical Embodiments of Light Emitting Device

Now, the light emitting device of the present invention will bedescribed in detail with reference to specific practical embodiments,but it should be understood that the present invention is by no meanslimited to the following practical embodiments and may be carried out byoptionally modifying them within the scope of the present invention.

FIG. 3 is a schematic perspective view showing the positional relationbetween a solid light emitting device (hereinafter sometimes referred toas a first illuminant) to be an excitation light source and a secondilluminant constructed as a phosphor-containing portion havingphosphors, in one embodiment of the light emitting device of the presentinvention. In FIG. 3, (1) represents the phosphor-containing portion(second illuminant), (2) represents a surface-emitting type GaN type LDas an excitation light source (first illuminant), and (3) represents asubstrate. In order to make a mutually contacted state, the LD (2) andthe phosphor-containing portion (second illuminant) (1) are separatelyprepared, and their surfaces may be bonded by an adhesive or by othermeans, or the phosphor-containing portion (second illuminant) may bedeposited (molded) on the emission surface of the LD (2). It is therebypossible to bring the LD (2) and the phosphor-containing portion (secondilluminant) (1) into contact with each other.

When such a device construction is taken, it is possible to avoid thelight quantity loss by leakage of the light from the excitation lightsource (first illuminant) as reflected on the film surface of thephosphor-containing portion (second illuminant), whereby the emissionefficiency of the entire device can be improved.

FIG. 4( a) is a schematic cross-sectional view showing one embodiment ofa light emitting device having an excitation light source (firstilluminant) and a phosphor-containing portion (second illuminant), whichis a typical example of a light emitting device of a form so-called ashell type. In the light emitting device (4), (5) represents a mountlead, (6) an inner lead, (7) an excitation light source (firstilluminant), (8) a phosphor-containing portion, (9) an electroconductivewire, and (10) a mold member.

Further, FIG. 4( b) is a schematic cross-sectional view showing oneembodiment of a light emitting device having an excitation light source(first illuminant) and a phosphor-containing portion (secondilluminant), which is a typical example of a light emitting device of aform so-called surface mount type. In the Fig., (15) represents a frame,(16) an electroconductive wire, and (17) and (18) electrodes.

Here, in a case where the above red-emitting phosphor is a fluoridecomplex phosphor, it is preferred that the light emitting device has atleast one of the following structures (a) to (c) with a view toimproving the light emitting device, specifically from such a viewpointthat deterioration with time of the light emitting device at atemperature of 85° C. under a humidity of 85% can be suppressed.

(a) a layer of a material not containing said fluoride complex phosphoris present between the solid light emitting device and the layercontaining said fluoride complex phosphor,

(b) part or whole of the surface of the light emitting device is coveredby a layer of a material not containing said fluoride complex phosphor,and

(c) the layer containing said fluoride complex phosphor is covered by alayer of a material not containing said fluoride complex phosphor.

The respective embodiments will be described in detail.

(3-4-1) Embodiment (a)

With respect to a light emitting device having the above structure (a),one embodiment is shown in FIG. 22 to describe it specifically.

In FIG. 22, a material layer C (112) which is a layer of material notcontaining a fluoride complex phosphor, is present on a semiconductorlight emitting device (110), and a material layer B (111) which is alayer containing a fluoride complex phosphor, is deposited thereon.

The material constituting the material layer C is not particularlylimited so long as it is a material having optical transparency and highchemical stability against heat, light and chemical reagents, but aresin is preferred from the viewpoint of availability and handlingefficiency.

Specifically, the resin to be used for the material layer C may, forexample, be a silicone resin, an epoxy resin, a fluorinated saturated orunsaturated aliphatic hydrocarbon resin, a polyolefin resin such aspolyethylene, or a polyester such as polycarbonate or polyethyleneterephthalate. Among them, a silicone resin is preferred from such aviewpoint that it has good adhesion with the semiconductor lightemitting device (110) and the fluoride complex phosphor-containing layer(111).

The silicone resin may be ones disclosed above with respect to theliquid medium. Among them, preferred may be an addition-type siliconeresin. Such a resin may specifically be SCR1011 or 1016 manufactured byShin-Etsu Chemical Co., Ltd.

The weight average molecular weight of the resin constituting thematerial layer C is usually at least 500, preferably at least 1,000 andusually at most 1,000,000, preferably at most 500,000, as measured by aGPC method.

Further, the thickness of the material layer C may depends also on thesize of the light emitting device (cup), but it is usually at least 100μm, preferably at least 200 μm, more preferably at least 250 μm andusually at most 500 μm, preferably at most 400 μm, more preferably atmost 300 μm. If the material layer C is too thin, the effects may not beobtainable. On the other hand, if it is too thick, such is not desirablefrom the viewpoint of the cost and the labor and time for production ofsuch a light emitting device.

As a production method, the LED chip (A) is fixed at the bottom of apackage, then a composition to constitute the material layer C isinjected on (A) to form a layer, and then a composition to constitutethe fluoride complex phosphor-containing layer (material layer B) isinjected. For the injection method, it is preferred to use a commonlyemployed injection device such as a dispenser.

(3-4-2) Embodiment (b)

With respect to a light emitting device having the above-mentionedstructure (b), some embodiments are shown in FIGS. 23( a) to 23(c) todescribe it specifically.

In FIG. 23( a), a material layer B (111) which is a fluoride complexphosphor-containing layer, is formed on a semiconductor light emittingdevice (110), and then a material layer D (113) which is a layer ofmaterial not containing a fluoride complex phosphor, is depositedthereon, thereby to cover the surface of the light emitting device.

Further, in FIG. 23( b), the embodiment disclosed in the above (3-4-1)is added to the embodiment of FIG. 23( a).

Further, FIG. 23( c) shows an embodiment wherein the material layer D(113) covers the entire light emitting device.

The material to constitute the above material layer D may, for example,be the same ones as disclosed for the above material layer C, but amaterial having a gas barrier property is preferred. That is, it isconsidered likely that hydrogen fluoride is formed in the light emittingdevice by a reaction of the fluoride complex phosphor with moisturewithin the light emitting device, and it may adversely affect theperformance of the light emitting device.

The material to constitute the material layer D may, for example, bepreferably a fluorinated saturated or unsaturated aliphatic hydrocarbonresin, a silicone resin or an epoxy resin, more preferably a fluorinatedsaturated or unsaturated aliphatic hydrocarbon resin or a siliconeresin. Such a fluorinated saturated or unsaturated aliphatic hydrocarbonresin may, for example, be EIGHT SEALS F-3000, manufactured by FlonIndustry Co., Ltd., fine heat resistant TFE coat manufactured by FlonIndustry Co., Ltd., or ALESFLON CLEAR manufactured by Kansai Paint Co.,Ltd. The silicone material may, for example, be SCR1011 or 1016manufactured by Shin-Etsu Chemical Co., Ltd.

Further, in a case where an epoxy resin is used for the material layerD, it is preferred to have a layer formed by another type of resin,between it and the material layer B, whereby its effects will be moredistinct.

The weight average molecular weight of the resin to constitute the abovematerial layer D is usually at least 500, preferably at least 1,000 andusually at most 1,000,000, preferably at most 500,000, as measured by aGPC method.

Further, the thickness of the above material layer D may depend also onthe size of the light emitting device, but it is usually at least 50 μm,preferably at least 80 μm, more preferably at least 100 μm, furtherpreferably at least 150 μm and usually at most 500 μm, preferably atmost 400 μm, more preferably at most 300 μm. If the material layer D istoo thin, the effects may not be obtainable. On the other hand, if it istoo thick, such is not desirable from the viewpoint of the cost and thelabor and time for production of such a light emitting device.

As a production method, the method may be adopted wherein the LED chip(A) is fixed at the bottom of a package, then a composition toconstitute the material layer D is injected on (A) to form a layer, andthen a composition to constitute the fluoride complexphosphor-containing layer (material layer B) is injected, or wherein alight emitting device is prepared and then, it is immersed in a curablematerial to constitute the material layer D, followed by curing.

(3-4-3) Embodiment (c)

With respect to a light emitting device having the above-mentionedstructure (c), one embodiment is shown in FIG. 24 to describe itspecifically.

In FIG. 24, the circumference of a material layer B (111) which is afluoride complex phosphor-containing layer, is covered by a materiallayer E (114) which is a layer of a material not containing a fluoridecomplex phosphor.

The material to constitute the material layer E is particularlypreferably one not having groups reactive with the fluoride complexphosphor, and it may, for example, be a fluorinated saturated orunsaturated hydrocarbon resin or a silicone resin.

The weight average molecular weight of the resin to constitute thematerial layer E as measured by a GPC method may, for example, be thesame one as the molecular weight of the resin to constitute theabove-mentioned material layers C and D.

Further, the thickness of the above material layer D may depend also onthe size of the light emitting device, but it is usually at least 1 μm,preferably at least 2 μm, more preferably at least 5 μm, furtherpreferably at least 10 μm and usually at most 50 μm, preferably at most30 μm, more preferably at most 20 μm.

As a production method, a method may be mentioned wherein the materiallayer E is formed around a preliminarily prepared material layer B by anoperation such as coating, and such an assembly is inserted in a cup ofthe light emitting device.

At that time, a portion other than the material layer B covered by thematerial layer E may be filled with the above-mentioned resin to formthe material layer C or D.

By adopting such a construction, the durability will be improved. Thereason is not clearly understood, but is considered to be such that byhaving such a specific layer, deterioration of the fluoride complexphosphor is suppressed and/or it is possible to lower a bypass currentaround the LED chip.

(3-5) Application of Light Emitting Device

Application of the light emitting device of the present invention is notparticularly limited, and it may be used in various fields whereincommon light emitting devices are employed. However, for such a reasonthat the color rendering is high or the color reproduction range isbroad, it is particularly useful as a light source for an illuminatingdevice or an image display device.

(3-5-1) Illuminating Device

In a case where the light emitting device of the present invention is tobe applied to an illuminating device, the light emitting device asdescribed above may be used as suitably assembled in a knownilluminating device. For example, a surface-emitting illuminating device(11) having the above-described light emitting device (4) assembledtherein as shown in FIG. 5, may be mentioned.

FIG. 5 is a cross-sectional view schematically showing one embodiment ofthe illuminating device of the present invention. As shown in FIG. 5, assuch the surface-emitting illuminating device (11) has many lightemitting devices (13) corresponding to the above-described lightemitting devices (4) on the bottom surface of a rectangular holding case(12) having its inner surface made to be non-light transmitting such asa white colored flat surface, and a power source, circuit, etc. (notshown) for driving the light emitting device (13) on its outside, and adiffusion plate (14) such as a milky white acryl plate is fixed at aportion corresponding to a cover of the holding case (12) to make theemission uniform.

And, the surface-emitting illuminating device (11) is driven to emitlight by applying a voltage to an excitation light source (firstilluminant) of the light emitting device (13). A part of the emission isabsorbed by the above-mentioned phosphors in the phosphor-containingresin portion as a phosphor-containing portion (second illuminant), andupon the absorption, the phosphors emit visible light. On the otherhand, by color mixing with e.g. blue light not absorbed by thephosphors, highly color rendering emission can be obtained. This lightpasses through the diffusion plate (14) and will be emitted upward inthe drawing, whereby it will be possible to obtain illumination lighthaving uniform brightness in the plane of the diffusion plate (14) ofthe holding case (12).

(3-5-2) Image Display Device

In a case where the light emitting device of the present invention isused as a light source for an image display device, the specificconstruction of its image display device is not particularly limited,but it is preferred to employ it together with a color filter. Forexample, in a case where the image display device is made to be a colorimage display device utilizing a color liquid crystal display element,it is possible to form the image display device by using the above lightemitting device as a backlight and combining it with optical shuttersusing liquid crystal and a color filter having red, green and bluepixels. This embodiment will be described below in further detail.

4. Color Image Display Device

With the light emitting device of the present invention, by combining itwith a color filter which is optimum to its emission wavelength, it ispossible to realize an image display having high color purity. That is,the above light emitting device is a light source where blue, green andred emissions with high emission peak intensities in narrow band regionsand excellent in temperature characteristics, are combined, whereby itis possible to obtain an excellent image display device having theemission peak intensity stabilized and having little color shift givenby employing a semiconductor light emitting device as a power devicewhich has a light use efficiency higher than ever even at a high NTSCratio and which becomes high temperature.

Now, one embodiment of the color image display device of the presentinvention will be described in detail.

The color image display device of the present invention is onecomprising a combination of light shutters, a color filter having colorelements of at least three colors of red, green and blue correspondingto the light shutters, and a backlight for transmission illumination.Its specific construction is not particularly limited. However, a colorliquid crystal display device of TFT (thin film transistor) type may,for example, be mentioned, which employs light shutters utilizing liquidcrystal, as shown in FIG. 6.

FIG. 6 shows an example of the color liquid crystal display device ofthe TFT type using a side-light type backlight device and a colorfilter. In this liquid crystal display device, light emitted from alight source (31) having the solid light emitting device and thephosphors, is converted to a surface light source by a light guide plate(32), a light diffusion sheet (33) further enhances uniformity of thelight, and the light then passes through a prism sheet to enter apolarizer (34). For this incident light, a direction of polarization iscontrolled in each pixel by TFT (36) and thereafter the light isincident into a color filter (39). Finally, the light entered into thecolor filter (39), passes through a polarizer (40) with the direction ofpolarization perpendicular to that of the polarizer (34) and thenreaches an observer. TFT (36) and the color filter (39) are,respectively, provided on glass substrates (35) and (38) which aretransparent substrates, and liquid crystal (37) is sealed in the spacebetween these glass substrates (35) and (38). The degree of change ofthe polarization direction of the incident light varies depending uponan applied voltage to TFT (36), so as to change the quantity of lightpassing through the polarizer (40), thus enabling display of a colorimage.

Further, the color image display device of the present invention ischaracterized in that by the construction which will be described belowin detail, the relationship between the light use efficiency Y shownbelow and the color reproduction range (NTSC ratio) W of the color imagedisplay device is represented by the following formula (a), preferably(b), more preferably (c), particularly preferably (d).

It is particularly preferred to use as the solid semiconductor lightemitting device, a solid light emitting device which emits light in adeep blue region or in an ultraviolet region, whereby the light useefficiency tends to be high.

Y≧−0.4W+64 (where W≧85)  (a)

Y≧−0.4W+66 (where W≧85)  (b)

Y≧−0.4W+71 (where W≧85)  (c)

Y≧−0.4W+73 (where W≦85)  (d)

$\begin{matrix}{X = \frac{\int_{380}^{780}{{\overset{\_}{x}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & {x = \frac{X}{X + Y + Z}} \\{Y = \frac{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & {y = \frac{Y}{X + Y + Z}} \\{Z = \frac{\int_{380}^{780}{{\overset{\_}{z}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & \;\end{matrix}$

wherein the definitions of the respective symbols are as follows:

x(λ), y(λ), z(λ): color matching functions of XYZ color system

S(λ): relative emission spectrum of the backlight

T(λ): transmittance of the color filter

That is, with a conventional color image display device, up to a NTSCratio of 85%, it was possible to control the light use efficiency tosome extent, but with a color image display device designed to have aNTSC ratio exceeding 85%, i.e. a NTSC ratio of at least 85%,particularly at least 87%, especially at least 90%, it was difficult toincrease the light use efficiency because of the pigment to be used fora resist of a conventional color filter or the emission spectrum of aphosphor, or the backlight spectrum obtained by a combination of a solidlight emitting device and a phosphor.

In the color image display device of the present invention, therelationship between the NTSC ratio W and the light use efficiency Y isset as follows.

(i) With a color image display device with a NTSC ratio exceeding 85%formed by a combination of a specific novel backlight and a colorfilter, the emission spectra of the respective phosphors used and theemission spectrum of the solid light emitting device (LED chip) arecombined to prepare an emission spectrum of a backlight. Based on theemission spectrum of the backlight, a virtual color filter is simulatedby calculation so that the NTSC ratio of the color image display devicewould be at least 85%.

(ii) With the virtual color image display device having the virtualcolor filter simulated in the above (i), the light use efficiency iscalculated at two points where the NTSC ratio would be at least 85%. Inthe present invention, two points of (NTSC ratio, light useefficiency)=(87.2%, 29.5%) and (91.6%, 27.7%) are calculated assimulated values when using β-SiAlON as a green emitting phosphor andK₂TiF₆:Mn as a red emitting phosphor.

(iii) from the above (ii), a linear function passing through the abovetwo points:

Y=−0.4W+64

is calculated, whereby the above-mentioned formula (a), i.e.

Y≧−0.4W+64 (where W≧85)  (a)

is obtained.

Further, a more preferred relationship between the NTSC ratio W and thelight use efficiency Y in a color image display device is obtainable insuch a manner that two points of (NTSC ratio, light useefficiency)=(87.2%, 29.5) and (91.6%, 27.7) are calculated as simulatedvalues when using Ba₃Si₆O₁₂N₂:Eu as a green emitting phosphor andK₂TiF₆:Mn as a red emitting phosphor, and from a linear function passingthrough the two points:

Y=−0.4W+66

the more preferred relation is obtainable as the above formula (b), i.e.

Y≧−0.4W+66 (where W≧85)  (b)

is obtained.

Further, in the case of using a near ultraviolet emitting LED as thesolid light emitting device, BaMgAl₁₀O₁₇:Eu as a blue emitting phosphor,BaMgAl₁₀O₁₇:Eu,Mn as a green emitting phosphor, and K₂TiF₆:Mn as a redemitting phosphor, the above formula (c) is obtainable in the samemanner as above.

Still further, in the case of using a near ultraviolet emitting LED asthe solid light emitting device, Sr₆(PO₄)₃Cl:Eu as a blue emittingphosphor, BaMgAl₁₀O₁₇:Eu,Mn as a green emitting phosphor, and K₂TiF₆:Mnas a red emitting phosphor, the above formula (d) is obtainable in thesame manner as above.

Further, also when K₂SiF₆:Mn is used as a red emitting phosphor, theabove formula can be obtained in the same manner.

A graph showing the relationships between the NTSC ratio and the lightuse efficiency, representing the formulae (a) to (d), is shown in FIG.7.

In the present invention, the light use efficiency Y can specifically becalculated by measuring the relative emission spectrum S(λ) of thebacklight by a high luminance measuring apparatus and the transmittancespectrum T(λ) of the color filter by a spectrophotometer, and byapplying the measured values to the above formulae.

Further, the color image display device of the present invention ischaracterized in that it has broad color reproducibility.

That is, the color image display device of the present inventioncomprises light shutters, a color filter having color elements of atleast three colors of red, green and blue corresponding to the lightshutters, and a backlight for transmission illumination, in combination.The light source for the backlight has a semiconductor light emittingdevice comprising a solid light emitting device which emits light in ablue or deep blue region or in an ultraviolet region, and phosphors, incombination, and the semiconductor light emitting device has at leastone main component of emission in each of the wavelength regions of from430 to 470 nm, from 500 to 550 nm and from 600 to 680 nm, whereby thecolor reproduction range of the color image display device is usually atleast 60% by NTSC ratio. The NTSC ratio is preferably at least 70%, morepreferably at least 80%, further preferably at least 85%, still morepreferably at least 87%, particularly preferably at least 90%.

Further, the color image display device of the present invention usuallyhas a color temperature of from 4,000 to 10,000 K, preferably from 4,500to 9,500 K, more preferably from 5,000 to 9,000 K. If the colortemperature is too low, the image tends to be entirely reddish. On theother hand, if the color temperature is too high, the brightness tendsto be low.

(4-1) Backlight Device

First, the construction of the backlight device to be used in a colorliquid crystal display device will be described.

The backlight device used in the present invention is a surface lightsource device disposed on a back face of a liquid crystal panel and usedas a back light source means for a transmission type orsemi-transmission type color liquid crystal display device.

As the specific construction, the backlight device comprises awhite-emitting light source and a light uniformizing means forconverting this light-source light into a nearly uniform surface lightsource.

Typical examples of the method for installation of the light sourceinclude a method of placing the light source immediately below the backface of the liquid crystal elements (direct backlight system), and amethod of placing the light source on a side face and using an opticallytransparent light guide such as an acrylic plate or the like to convertthe light into surface light to obtain a surface light source (sidelight system). Among them, the side light system as shown in FIGS. 8 and9 is suitably applicable as a surface light source being thin andexcellent in uniformity of luminance distribution, and is now mostcommonly put to practical use.

The backlight device of FIG. 8 is constructed so that a light source(31) is placed along one side end face (41 a) of a substrate consistingof an optically transparent flat plate, i.e., a light guide (41), andlight is permitted to enter through one side end face (41 a) as a lightentrance face into the interior of the light guide (41). One surface (41b) of the light guide (41) serves as a light exit face, and a lightcontrol sheet (43) with an array (42) of nearly triangular prism shapeformed therein is placed above the light exit face (41 b) so that apexangles of the array (42) are directed toward the observer. A lightextracting mechanism (44) printed in a predetermined pattern of manydots (44 a) of light scattering ink is provided on the other face (41 c)opposite to the light exit face (41 b) in the light guide (41). On thisface (41 c) side, a reflecting sheet (45) is provided in proximity tothis face (41 c).

The backlight device of FIG. 9 is constructed in much the sameconstruction as the backlight device shown in FIG. 8, except that thelight control sheet (43) with the prism array (42) of nearly triangularprism shape formed therein is located so that the apex angles of thearray (42) are directed toward the light exit face (41 b) of the lightguide (41) and except that the light extracting mechanism (44′) providedin the face (41 c) opposite to the light exit face (41 b) of the lightguide (41) is comprised of a rough pattern (44 b) with each surfacebeing formed as a rough surface.

By adopting the backlight devices of the side light system as describedabove, it is feasible to bring out the lightweight and low-profilefeatures of the liquid crystal display device more effectively.

As the light source of the backlight device of this invention, theabove-described light emitting device may be used, and it may containLED in its structure. As such a light source, any one may usually beused so long as it is of a type to provide emissions within the red,green and blue wavelength regions i.e. within the ranges of from 580 to700 nm, from 500 to 550 nm and from 400 to 480 nm.

For the backlight to satisfy such conditions, the light source has asemiconductor light emitting device comprising one or plural solid lightemitting devices to emit light in a blue or deep blue region or in anultraviolet region, and phosphors to be excited by light from such solidlight emitting devices, in combination. The semiconductor light emittingdevice is adjusted so that it has at least one emission main peak ineach wavelength region of the red region (region of usually at least 600nm, preferably at least 610 nm, more preferably at least 620 nm andusually at most 680 nm, preferably at most 670 nm, further preferably atmost 650 nm), the green region (region of usually at least 500 nm,preferably at least 510 nm and usually at most 550 nm, preferably atmost 542 nm, more preferably at most 540 nm, further preferably at most535 nm, more preferably at most 530 nm, particularly preferably at most525 nm, especially preferably at most 520 nm) and the blue region(region of usually at least 430 nm, preferably at least 440 nm andusually at most 470 nm, preferably at most 460 nm).

The light quantity in each region of red, green and blue in atransmissive or semi-transmissive transparent mode, is determined by theproduct of the emission from the backlight and the spectraltransmittance of the color filter. Accordingly, it is necessary toselect the backlight to satisfy the conditions which will be describedhereinafter in the section (c) Colorant for the composition for a colorfilter.

(4-2) Color Filter

The color filter to be used for the color image display device of thepresent invention is not particularly limited, and for example, thefollowing one may be employed.

The color filter is a fitter obtained by forming fine pixels of red,green, blue and so on on a transparent substrate of glass or the like bya method of dyeing, printing, electrodeposition, pigment dispersion, orthe like. In order to block leaking light between these pixels andobtain images with higher quality, it is often the case to provide alight shielding pattern called a black matrix between pixels.

A color filter by dyeing is fabricated in such a manner that an image isformed by a photosensitive resin obtained by mixing a bichromate as aphotosensitive agent into gelatin, polyvinyl alcohol, or the like,followed by dyeing.

A color filter by printing is fabricated by transferring a heat-curingor photo-curing ink onto a transparent substrate of glass or the like bysuch a method as screen printing, gravure printing, flexographicprinting, inversion printing or soft lithography (imprint printing).

A color filter by electrodeposition is formed by electrophoresiseffected while a transparent substrate of glass or the like with anelectrode thereon is immersed in a bath containing a pigment or a dye.

A color filter by pigment dispersion is formed by applying a compositionin which a colorant such as a pigment is dispersed or dissolved in aphotosensitive resin, onto a transparent substrate of glass or the liketo form a coating film thereon, exposing the coating film to radiationthrough a photomask to effect exposure, and removing unexposed portionsby a development process to form a pattern.

The color filter can also be fabricated by other methods than these,including a method of applying a polyimide type resin composition inwhich a colorant is dispersed or dissolved, and forming a pixel image byetching, a method of attaching a film coated with a resin compositioncontaining a colorant, to a transparent substrate, peeling it off, andeffecting image exposure and development to form a pixel image, a methodof forming a pixel image by an ink jet printer, and so on.

In recent years, the pigment dispersion method is mainstream infabrication of the color filters for liquid crystal display elements byvirtue of its high productivity and excellent microfabrication property,but the color filter according to the present invention can befabricated by any one of the above-mentioned production methods.

Examples of methods of forming the black matrix include a method offorming a chromium and/or chromium oxide (single-layer or multi-layer)film over an entire surface of a transparent substrate of glass or thelike by a method such as sputtering, and thereafter removing only colorpixel portions by etching, a method of applying a photosensitivecomposition in which a light shielding component is dispersed ordissolved, onto a transparent substrate of glass or the like to form acoating film, exposing the coating film to radiation through a photomaskto effect exposure, and removing unexposed portions by development toform a pattern, and so on.

(4-2-1) Method for Producing Color Filter

Now, a specific example of the method for producing the color filter ofthe present invention will be described.

The color filter of the present invention can be produced usually byforming red, green and blue pixel images on a transparent substrateprovided with a black matrix. At the time of forming the respectivecolor pixels on the transparent substrate, pigments and film thicknessesare optimized basically in order to let the peak wavelengths in the red,blue and green regions in the emission spectrum of the backlightpermeate most efficiently. More specifically, the most suitable pigmentsand film thicknesses are set by calculating the white point, the colorindex of the spectrum of the backlight and the desired NTSC ratio, by acolor matching system.

The material for the transparent substrate is not particularly limited.The material may, for example, be a polyester such as polyethyleneterephthalate; a polyolefin such as polyethylene, polypropylene; athermoplastic sheet of e.g. polycarbonate, polymethyl methacrylate orpolystyrene; a thermosetting sheet of e.g. an epoxy resin, anunsaturated polyester resin or a poly(meth)acrylic resin; and variousglass plates. Among them, a glass plate or a heat resistant plastic ispreferred from the viewpoint of heat resistance.

To the transparent substrate, in order to improve the physical propertysuch as the adhesive property of the surface, corona dischargetreatment, ozone treatment or thin film treatment with a silane couplingagent or various polymers such as urethane polymer may be preliminarilyapplied.

A black matrix is formed on a transparent substrate by using a metalthin film or a pigment dispersion for black matrix.

The black matrix using a metal thin film may, for example, be formed bya single chromium layer or by two layers of chromium and chromium oxide.In such a case, firstly, a thin film of such a metal or metal-metaloxide is formed on the transparent substrate by vapor deposition orsputtering. Then, a photosensitive coating film is formed thereon, andthen, by using a photomask having a repeated pattern of a stripe,mosaic, triangle, etc., the photosensitive coating film is exposed anddeveloped to form a resist image. Then, the thin film is subjected toetching treatment to form a black matrix.

In a case where a pigment dispersion for black matrix is to be used, acomposition for a color filter containing a black colorant is used as acolorant to form a black matrix. For example, black colorants such ascarbon black, graphite, iron black, aniline black, cyanine black andtitanium black may be used alone or in combination as a mixture of aplurality of them, or a composition for a color filter containing ablack colorant by mixing red, green, blue, etc. suitably selected frominorganic or organic pigments or dyes, is used to form a black matrix inthe same manner as the following method for forming red, green and bluepixel images.

On the transparent substrate provided with the black matrix, the abovementioned composition for a color filter containing one colorant amongred, green and blue, is applied and dried, and then, a photomask isplaced on this coating film, and the image exposure via the photomask,development and if necessary, heat-curing or photo-curing are carriedout to form pixel images to form a colored layer. This operation iscarried out for each of color filter compositions for three colors ofred, green and blue to form a color filter image.

Application of the color filter composition can be carried out by acoating device such as a spinner, a wire bar, a flow coater, a diecoater, a roll coater or a spray.

The drying after the coating, may be carried out by using a hot plate,an IR oven, or a convection oven. With respect to the dryingtemperature, the adhesive property to the transparent substrate will beimproved as the temperature becomes high. However, if it is too high,the after-mentioned photo polymerization initiator system tends to bedecomposed, thus inducing heat polymerization to cause developmentfailure. Therefore, the drying temperature is usually within a range offrom 50 to 200° C., preferably from 50 to 150° C. Further, the dryingtime is usually from 10 seconds to 10 minutes, preferably from 30seconds to 5 minutes. Further, prior to such drying by a heat, it isalso possible to apply a drying method under reduced pressure.

The thickness of the coating film after the drying, i.e. the thicknessof each pixel, is within a range of usually from 0.5 to 3.5 μm,preferably from 1.0 to 3.0 μm. If the film thickness is too thick,non-uniformity in the film thickness tends to be large, and if it is toothin, the pigment concentration tends to be high, and it tends to bedifficult to form images.

In the present invention, the light use efficiency of the backlight isexcellent, whereby the color filter may be made thin. By making thecolor filter thin, it is possible to shorten the time and simplify theproduction steps, thus leading to improvement of the productivity andreduction of the price, and it is also possible to save the powerconsumption of the backlight when operated as a display panel. Further,it is possible to realize a thin image display device, and it isparticularly suitable for a cell phone whereby a thin-form is requiredfor the device itself.

Further, the composition for the color filter to be used comprises abinder resin and an ethylenic compound, and when the binder resin is anacrylic resin having ethylenic double bonds and carboxyl groups in sidechains, a very high sensitivity and a high resolution are obtainable,whereby an image may be formed by exposure and development withoutproviding an oxygen-shielding layer of e.g. polyvinyl alcohol, suchbeing desirable.

The exposure light source useful for the image exposure is notparticularly limited. For example, a lamp light source such as a xenonlamp, a halogen lamp, a tungsten lamp, a high pressure mercury lamp, asuper high pressure mercury lamp, a metal halide lamp, a medium pressuremercury lamp, a low pressure mercury lamp, a carbon arc or a fluorescentlamp; or a laser light source such as an argon ion laser, a YAG laser,an excimer laser, a nitrogen laser, a helium cadmium laser or asemiconductor laser, may be used. An optical filter may be used in acase where only a certain wavelength is to be used.

After the image exposure by means of such a light source, development iscarried out by means of an organic solvent, or an aqueous solutioncontaining a surfactant and an alkali agent, to form an image on thesubstrate. Such an aqueous solution may further contain an organicsolvent, a buffering agent, a dye, a pigment, etc.

The treating method for the development is not particularly limited, butusually, a method of immersion development, spray development, brushdevelopment or ultrasonic wave development may be used at a developmenttemperature of usually from 10 to 50° C., preferably from 15 to 45° C.

The alkali agent to be used for the development may, for example, be aninorganic alkali agent such as sodium silicate, potassium silicate,sodium hydroxide, potassium hydroxide, lithium hydroxide, sodiumtriphosphate, sodium diphosphate, sodium carbonate, potassium carbonate,or sodium bicarbonate, or an organic amine such as trimethylamine,diethylamine, isopropylamine, n-butylamine, monoethanolamine,diethanolamine, triethanolamine or tetraalkylammonium hydroxide. Theymay be used alone or in combination as a mixture of two or more of them.

As the surfactant, a nonionic surfactant such as a polyoxyethylene alkylether, a polyoxyethylene alkyl aryl ether, a polyoxyethylene alkylester, a sorbitan alkyl ester, a monoglyceride alkyl ester; an anionicsurfactant such as an alkylbenzene sulfonate, an alkylnaphthalenesulfonate, an alkyl sulfate, an alkyl sulfonate or a sulfosuccinate; oran amphoteric surfactant such as an alkylbetaine or an amino acid, maybe used.

The organic solvent may be used alone or in combination with an aqueoussolution, and in either case, isopropyl alcohol, benzyl alcohol, ethylcellosolve, butyl cellosolve, phenyl cellosolve, propylene glycol ordiacetone alcohol may, for example, be used.

(4-3) Composition for Color Filter

The composition (resist) for a color filter to be used for the colorimage display device of the present invention is not particularlylimited, and the following one may, for example, be used.

Raw materials for production of the color filter will be describedbelow, using an example of the pigment dispersion method which iscommonly used.

The pigment dispersion method uses a composition in which a colorantsuch as a pigment is dispersed in a photosensitive resin as describedabove (hereinafter called a “composition for a color filter”). Thiscomposition for a color filter is generally a color composition for acolor filter in which (a) a binder resin and/or (b) a monomer, (c) acolorant and (d) other components are dissolved or dispersed as theconstituting components in a solvent.

Each of the components will be described below in detail. In thedescription below, “(meth)acryl”, “(meth)acrylate” and “(meth)acrylol”mean “acryl or methacryl”, “acrylate or methacrylate” and “acrylol ormethacrylol”, respectively.

(a) Binder Resin

Where a binder resin is used singly, an appropriate one is properlyselected in consideration of the desired image forming property andperformance, a production method desired to adopt, and so on. Where abinder resin is used in combination with a monomer described later, thebinder resin is added in order to modify the composition for a colorfilter and improve the physical properties after photo-curing. In thiscase, therefore, a binder resin is properly selected depending upon thepurpose for improvement such as compatibility, a film forming property,a development property, an adhesion property, or the like.

The binder resins usually used are, for example, homopolymers orcopolymers of (meth)acrylic acid, (meth)acrylate esters,(meth)acrylamide, maleic acid, (meth)acrylonitrile, styrene, vinylacetate, vinylidene chloride, maleimide, and so on, polyethylene oxides,polyvinyl pyrrolidones, polyamides, polyurethanes, polyesters,polyethers, polyethylene terephthalates, acetylcelluloses, novolakresins, resol resins, polyvinyl phenols, polyvinyl butyrals, and so on.

Among these binder resins, preferred binder resins are those having acarboxyl group or a phenolic hydroxyl group in a side chain or in themain chain thereof. Development in an alkali solution becomes possiblewith use of the resins having these functional groups. Among them,preferred binder resins are resins having a carboxyl group, which have ahigh alkali development property; for example, homo- or co-polymers ofacrylic acid, resins of styrene/maleic anhydride, resins of novolakepoxy acrylate modified with an acid anhydride, and so on.

Particularly preferred binder resins are homo- or co-polymers containing(meth)acrylic acid or a (meth)acrylate ester having a carboxyl group(these will be referred to as “acrylic resins” in the presentinvention). Namely, these acrylic resins are preferred in terms of easycontrollability of performance and a production method because they areexcellent in the development property and transparency and can providevarious copolymers from a wide range of monomers.

Specific examples of the acrylic resins include resins that comprise, asan essential component, (meth)acrylic acid and/or a compound obtained byadding an acid (anhydride), such as (anhydrous) succinic acid,(anhydrous) phthalic acid, (anhydrous) maleic acid, or the like, to ahydroxyalkyl(meth)acrylate, such as succinic acid(2-(meth)acryloyloxyethyl) ester, adipic acid (2-acryloyloxyethyl)ester, phthalic acid (2-(meth)acryloyloxyethyl) ester, hexahydrophthalicacid (2-(meth)acryloyloxyethyl) ester, maleic acid(2-(meth)acryloyloxyethyl) ester, succinic acid(2-(meth)acryloyloxypropyl) ester, adipic acid(2-(meth)acryloyloxypropyl) ester, hexahydrophthalic acid(2-(meth)acryloyloxypropyl) ester, phthalic acid(2-(meth)acryloyloxypropyl) ester, maleic acid(2-(meth)acryloyloxypropyl) ester, succinic acid(2-(meth)acryloyloxybutyl) ester, adipic acid (2-(meth)acryloyloxybutyl)ester, hexahydrophthalic acid (2-(meth)acryloyloxybutyl) ester, phthalicacid (2-(meth)acryloyloxybutyl) ester, maleic acid(2-(meth)acryloyloxybutyl) ester, or the like; and that arecopolymerized, if necessary, with one of various monomers, e.g., styrenetype monomers such as styrene, α-methylstyrene, vinyltoluene, and so on;unsaturated group-containing carboxylic acids such as cinnamic acid,maleic acid, fumaric acid, maleic anhydride, itaconic acid, and so on;(meth)acrylate esters such as methyl (meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, allyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, hydroxyethyl (meth)acrylate,hydroxypropyl(meth)acrylate, benzyl (meth)acrylate,hydroxyphenyl(meth)acrylate, methoxyphenyl (meth)acrylate, and so on;compounds obtained by adding to (meth)acrylic acid, one of lactones suchas ε-caprolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone,and so on; acrylonitrile; acrylamides such as (meth)acrylamide,N-methylolacrylamide, N,N-dimethylacrylamide, N-methacryloyl morpholine,N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethylacrylamide,and so on; vinyl acids such as vinyl acetate, vinyl versatate, vinylpropionate, vinyl cinnamate, vinyl pivalate, and so on.

For a purpose of increasing the strength of the coating film, acrylicresins preferably used are those obtained by copolymerization of from 10to 98 mol %, preferably from 20 to 80 mol %, more preferably from 30 to70 mol %, of one of monomers having a phenyl group, such as styrene,α-methylstyrene, benzyl (meth)acrylate, hydroxphenyl(meth)acrylate,methoxyphenyl(meth)acrylate, hydroxyphenyl(meth)acrylamide,hydroxyphenyl(meth)acrylsulfoamide, and so on, and from 2 to 90 mol %,preferably from 20 to 80 mol %, more preferably from 30 to 70 mol %, ofat least one monomer selected from the group consisting of (meth)acrylicacid, or (meth)acrylates having a carboxyl group, such as succinic acid(2-(meth)acryloyloxyethyl) ester, adipic acid (2-acryloyloxyethyl)ester, phthalic acid (2-(meth)acryloyloxyethyl) ester, hexahydrophthalicacid (2-(meth)acryloyloxyethyl) ester, maleic acid(2-(meth)acryloyloxyethyl) ester, and so on.

In addition, these binder resins preferably have an ethylenic doublebond in a side chain. By using a binder resin having a double bond in aside chain, the photo-curing property of the composition for a colorfilter obtained is enhanced, whereby it is feasible to further improvethe resolving property and adhesion property.

Means for introducing an ethylenic double bond into a binder resininclude, for example, methods disclosed in JP-B-50-34443, JP-B-50-34444,and so on; i.e., a method of reacting a compound having both a glycidylgroup/an epoxy cyclohexyl group, and a (meth)acryloyl group with acarboxylic group of a resin, and a method of reacting an acrylic acidchloride or the like with a hydroxyl group of a resin.

For example, a binder resin having an ethylenic double bond in a sidechain is obtained by reacting a compound, such asglycidyl(meth)acrylate, allyl glycidyl ether, glycidyl α-ethylacrylate,crotonyl glycidyl ether, (iso)crotonic acid glycidyl ether,(3,4-epoxycyclohexyl)methyl (meth)acrylate, (meth)acrylic acid chloride,or (meth)acryl chloride, with a resin having a carboxyl group or ahydroxyl group. Particularly preferred binder resins are those resultingfrom a reaction with an alicyclic epoxy compound such as (3,4-epoxycyclohexyl)methyl (meth)acrylate.

When an ethylenic double bond is preliminarily introduced into a resinhaving a carboxylic group or hydroxyl group as described above, it ispreferable to bond a compound having an ethylenic double bond to from 2to 50 mol %, preferably from 5 to 40 mol %, of the carboxyl group orhydroxyl group in the binder resin.

These acrylic resins preferably have a weight-average molecular weight,as measured by GPC (gel permeation chromatography), in a range of from1,000 to 100,000. If the weight-average molecular weight is less than1,000, it tends to be difficult to obtain a uniform film. On the otherhand, if it exceeds 100,000, the development property tends to degrade.A preferred content of the carboxylic group is in a range of from 5 to200 as an acid value (mgKOH/g). If the acid value is less than 5, theresin tends to be insoluble in an alkali developer. On the other hand,if it exceeds 200, the sensitivity may become lower.

As the binder resin, particularly preferred specific examples will bedescribed below.

(a-1): “Alkali-Soluble Resin Obtainable by Adding an UnsaturatedMonobasic Acid to at Least Some of Epoxy Groups in a Copolymer of anEpoxy Group-Containing (Meth)Acrylate with Another Radical PolymerizableMonomer, and Further Adding a Polybasic Acid Anhydride to at Least Someof Hydroxyl Groups Formed by the Above Addition Reaction”

As such a resin, a resin disclosed in JP-A-2005-154708, paragraphs 0090to 0110, may, for example, be mentioned.

(a-2): “Carboxyl Group-Containing Linear Alkali-Soluble Resin”

As the carboxyl group-containing linear alkali-soluble resin is notparticularly limited so long as it has carboxyl groups, and such a resinis usually obtained by polymerizing a polymerizable monomer having acarboxyl group. As such a resin, a resin disclosed in JP-A-2005-232432,paragraphs 0055 to 0066, may, for example, be mentioned.

(a-3): “A Resin Having an Epoxy Group-Containing Unsaturated CompoundAdded to Carboxyl Group Moieties of the Above Mentioned (a-2) Resin”

A resin having an epoxy group-containing unsaturated compound added tocarboxyl group moieties of the above carboxyl group-containing resin(a-2), is particularly preferred.

The epoxy group-containing unsaturated compound is not particularlylimited so long as it is one having an ethylenic unsaturated group andan epoxy group in its molecule.

For example, a non-cyclic epoxy group-containing unsaturated compoundsuch as glycidyl (meth)acrylate, allyl glycidyl ether,glycidyl-α-ethylacrylate, crotonyl glycidyl ether, (iso)crotonic acidglycidyl ether, N-(3,5-dimethyl-4-glycidyl)benzylacrylamide or4-hydroxybutyl (meth)acrylate glycidyl ether, may also be mentioned.However, from the viewpoint of the heat resistance and theafter-mentioned dispersibility of pigment, an alicyclic epoxygroup-containing unsaturated compound is preferred.

Here, as the alicyclic epoxy group-containing unsaturated compound, itsalicyclic epoxy group may, for example, be a 2,3-epoxycyclopentyl group,a 3,4-epoxycyclohexyl group or a 7,8-epoxy{tricyclo[5.2.1.0]decy-2-yl}group.

Further, as the ethylenic unsaturated group, one derived from a(meth)acryloyl group is preferred. Particularly preferred is3,4-epoxycyclohexyl methyl (meth)acrylate.

As such a resin, a resin disclosed in JP-A-2005-232432, paragraphs 0055to 0066, may, for example, be mentioned.

(a-4): “Acrylic Resin”

As a preferred acrylic resin, a resin disclosed in JP-A-2006-161035,paragraphs 0067 to 0086, may for example, be mentioned.

Such a binder resin is contained within a range of usually from 10 to 80wt %, preferably from 20 to 70 wt %, in the total solid content of thecomposition for a color filter.

(b) Monomer

There is no particular restriction on the monomer as long as it is apolymerizable low molecular weight compound. A preferred monomer is anaddition-polymerizable compound having at least one ethylenic doublebond (hereinafter, abbreviated as an “ethylenic compound”). Theethylenic compound is a compound having an ethylenic double bond whichis addition-polymerized by the action of a photopolymerization initiatorsystem as described hereinafter, to cure when the composition for acolor filter is exposed to active lights. Here the monomer in thepresent invention implies a concept obverse to a so-called polymersubstance and implies a concept embracing not only monomers in a narrowsense but also dimers, trimers, and oligomers.

The ethylenic compound may be, for example, an unsaturated carboxylicacid, an ester of an unsaturated carboxylic acid with a monohydroxycompound, an ester of an aliphatic polyhydroxy compound with anunsaturated carboxylic acid, an ester of an aromatic polyhydroxycompound with an unsaturated carboxylic acid, an ester obtained by anesterification reaction of an unsaturated carboxylic acid and apolybasic carboxylic acid with a polyhydric hydroxy compound such as theaforementioned aliphatic polyhydroxy compound or aromatic polyhydroxycompound, an ethylenic compound with a urethane skeleton obtained byreacting a polyisocyanate compound with a (meth)acryloyl-containinghydroxy compound, or the like.

The unsaturated carboxylic acid may be, for example, (meth)acrylic acid,(anhydrous) maleic acid, crotonic acid, itaconic acid, fumaric acid,2-(meth)acryloyloxyethyl succinic acid, 2-acryloyloxyethyl adipic acid,2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl maleic acid,2-(meth)acryloyloxypropyl succinic acid, 2-(meth)acryloyloxypropyladipic acid, 2-(meth)acryloyloxypropyl hydrophthalic acid,2-(meth)acryloyloxypropyl phthalic acid, 2-(meth) acryloyloxypropylmaleic acid, 2-(meth)acryloyloxybutyl succinic acid,2-(meth)acryloyloxybutyl adipic acid, 2-(meth)acryloyloxybutylhydrophthalic acid, 2-(meth)acryloyloxybutyl phthalic acid, 2-(meth)acryloyloxybutyl maleic acid, a monomer obtained by adding to(meth)acrylic acid one of lactones such as ε-caprolactone,β-propiolactone, γ-butyrolactone, δ-valerolactone, and so on, a monomerobtained by adding to a hydroxyalkyl(meth)acrylate, an acid (anhydride)such as (anhydrous) succinic acid, (anhydrous) phthalic acid or(anhydrous) maleic acid, or the like. Among them, (meth)acrylic acid and2-(meth)acryloyloxyethyl succinic acid are preferred, and (meth)acrylicacid is more preferred. These may be used in combination of two or more.

The ester of an aliphatic polyhydroxy compound with an unsaturatedcarboxylic acid may be an acrylate such as ethylene glycol diacrylate,triethylene glycol diacrylate, trimethylolpropane triacrylate,trimethylolethane triacrylate, pentaerythritol diacrylate,pentaerythritol triacrylate, pentaerythritol tetraacrylate,dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate,dipentaerythritol hexaacrylate, glycerol acrylate, or the like. Further,the ester may be a methacrylate, an itaconate, a crotonate or a maleateobtained by replacing the acrylic acid moiety of the aforementionedacrylates with a methacrylic acid moiety, an itaconic acid moiety, acrotonic acid moiety or a maleic acid moiety, respectively.

The ester of an aromatic polyhydroxy compound with an unsaturatedcarboxylic acid may be hydroquinone diacrylate, hydroquinonedimethacrylate, resorcin diacrylate, resorcin dimethacrylate, pyrogalloltriacrylate, or the like.

The ester obtained by an esterification reaction of an unsaturatedcarboxylic acid and a polybasic carboxylic acid with a polyhydrichydroxy compound is not necessarily a single substance, but it may be amixture. Typical examples of the ester include a condensation product ofacrylic acid, phthalic acid and ethylene glycol, a condensation productof acrylic acid, maleic acid and diethylene glycol, a condensationproduct of methacrylic acid, terephthalic acid and pentaerythritol, acondensation product of acrylic acid, adipic acid, butanediol andglycerol, and so on.

The ethylenic compound with a urethane skeleton obtained by reacting apolyisocyanate compound and a (meth)acryloyl group-containing hydroxycompound may be a reaction product of an aliphatic diisocyanate such ashexamethylene diisocyanate, trimethylhexamethylene diisocyanate, or thelike; an alicyclic diisocyanate such as cyclohexane diisocyanate,isophorone diisocyanate, or the like; an aromatic diisocyanate such astolylene diisocyanate, diphenylmethane diisocyanate, or the like, with a(meth)acryloyl group-containing hydroxy compound such as 2-hydroxyethylacrylate, 2-hydroxyethyl methacrylate,3-hydroxy(1,1,1-triacryloyloxymethyl) propane,3-hydroxy(1,1,1-trimethacryloyloxymethyl) propane, or the like.

Other examples of the ethylenic compound used in the present inventioninclude acryl amides such as ethylenebisacrylamide; allyl esters such asdiallyl phthalate; vinyl group-containing compounds such as divinylphthalate.

The compounding rate of the ethylenic compounds is usually in a range offrom 10 to 80% by weight, preferably in a range of from 20 to 70% byweight, relative to the total solid content of the composition for acolor filter.

(c) Colorant

In order to utilize the light from the backlight as effectively aspossible, it is necessary to select a colorant so that, in accordancewith the red, green and blue emission wavelengths of the backlight, thetransmittance at the emission wavelengths of the phosphor in each colorpixel becomes as high as possible, while the transmittance becomes aslow as possible at the other emission wavelengths.

The present invention is characterized particularly by a high colorreproducibility not available by conventional LED backlight, andaccordingly, a due care is required for the selection of the colorants.Namely, in order to sufficiently utilize the characteristics of abacklight having deep red and green emission wavelengths characteristicto the present invention, it is required to satisfy the followingconditions.

(4-3-1) Red Composition

Firstly, a red composition (red resist) constituting red pixels will bedescribed.

-   -   The pigments to be used for the red composition in the present        invention, may be organic pigments, such as azo type,        quinacridone type, benzimidazolone type, isoindoline type,        perylene type and diketopyrrolopyrol type pigments, and, in        addition thereto, various inorganic pigments.    -   Specifically, pigments having the following pigment numbers may,        for example, be used. Here, the term “C. I.” below means a color        index (C. I.).

Red colorant: C. I. pigment red 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 14, 15,16, 17, 21, 22, 23, 31, 32, 37, 38, 41, 47, 48, 48:1, 48:2, 48:3, 48:4,49, 49:1, 49:2, 50:1, 52:1, 52:2, 53, 53:1, 53:2, 53:3, 57, 57:1, 57:2,58:4, 60, 63, 63:1, 63:2, 64, 64:1, 68, 69, 81, 81:1, 81:2, 81:3, 81:4,83, 88, 90:1, 101, 101:1, 104, 108, 108:1, 109, 112, 113, 114, 122, 123,144, 146, 147, 149, 151, 166, 168, 169, 170, 172, 173, 174, 175, 176,177, 178, 179, 181, 184, 185, 187, 188, 190, 193, 194, 200, 202, 206,207, 208, 209, 210, 214, 216, 220, 221, 224, 230, 231, 232, 233, 235,236, 237, 238, 239, 242, 243, 245, 247, 249, 250, 251, 253, 254, 255,256, 257, 258, 259, 260, 262, 263, 264, 265, 266, 267, 268, 269, 270,271, 272, 273, 274, 275, 276.

Further, for fine adjustment of the color, the following yellow colorantmay be mixed to the above red colorant.

Yellow colorant: C. I. pigment yellow 1, 1:1, 2, 3, 4, 5, 6, 9, 10, 12,13, 14, 16, 17, 24, 31, 32, 34, 35, 35:1, 36, 36:1, 37, 37:1, 40, 41,42, 43, 48, 53, 55, 61, 62, 62:1, 63, 65, 73, 74, 75, 81, 83, 87, 93,94, 95, 97, 100, 101, 104, 105, 108, 109, 110, 111, 116, 119, 120, 126,127, 127:1, 128, 129, 133, 134, 136, 138, 139, 142, 147, 148, 151, 153,154, 155, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168,169, 170, 172, 173, 174, 175, 176, 180, 181, 182, 183, 184, 185, 188,189, 190, 191, 191:1, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202,203, 204, 205, 206, 207, 208, etc.

(4-3-2) Green Composition

Now, a green composition (green resist) constituting green pixels willbe described.

The pigments to be used for the green composition of the presentinvention may be organic pigments, such as azo type and phthalocyaninetype pigments, and, in addition thereto, various inorganic pigments.

Specifically, pigments having the following pigment numbers may, forexample, be used.

Green colorant: C. I. pigment green 1, 2, 4, 7, 8, 10, 13, 14, 15, 17,18, 19, 26, 36, 45, 48, 50, 51, 54, 55, and a zinc phthalocyaninebromide pigment.

Further, for fine adjustment of the color, the above mentioned yellowcolorant may be mixed to the above green colorant.

As green pixels, a specific example to satisfy the above conditionspreferably comprises pigment green 36, pigment green 7 and/or a zincphthalocyanine bromide pigment as a green pigment, and at least one ofan azo nickel complex yellow pigment, pigment yellow 138 and pigmentyellow 139, as a yellow pigment for color adjustment. Further, pigmentgreen 58 is preferred as the zinc phthalocyanine bromide pigment.

Further, in the present invention, in a case where a color image displaydevice having a NTSC ratio of at least 85%, particularly at least 90%,is to be prepared, it is preferred to employ pigment green 7 or zincphthalocyanine bromide pigment instead of pigment green 36 from theviewpoint of the transmittance. The zinc phthalocyanine bromide ispreferably a zinc phthalocyanine bromide containing at least 13 bromineatoms per molecule on average, since it shows high transmittance andthus is suitable for forming a green pixel for a color filter. Morepreferred is a zinc phthalocyanine bromide having from 13 to 16 bromineatoms per molecule and containing no chlorine or having at most 3chlorine atoms per molecule on average, and particularly preferred is azinc phthalocyanine bromide having from 14 to 16 bromine atoms permolecule on average and containing no chlorine or having at most 2chlorine atoms per molecule on average. Table 9 shows preferred blendexamples (wt %) of colorants constituting green pixels.

TABLE 9 zinc phthalo- Azo nickel Pigment Pigment cyanine complex yellowClear green 36 green 7 bromide pigment* resist Blend 14.3 22.6 63.1Example 1 Blend 9.8 22.1 68.1 Example 2 Blend 18.0 17.0 65.1 Example 3*Disclosed in JP-A-2007-25687

(4-3-3) Blue Composition

Now, a blue composition (blue resist) constituting blue pixels will bedescribed.

As pigments to be used for the blue composition of the presentinvention, pigments having the following pigment numbers may, forexample, be used.

Blue colorant: C. I. pigment blue 1, 1:2, 9, 14, 15, 15:1, 15:2, 15:3,15:4, 15:6, 16, 17, 19, 25, 27, 28, 29, 33, 35, 36, 56, 56:1, 60, 61,61:1, 62, 63, 66, 67, 68, 71, 72, 73, 74, 75, 76, 78, 79

Violet colorant: C. I. pigment violet 1, 1:1, 2, 2:2, 3, 3:1, 3:3, 5,5:1, 14, 15, 16, 19, 23, 25, 27, 29, 31, 32, 37, 39, 42, 44, 47, 49, 50

(4-3-4) Adjustment of Color Composition

Further, irrespective of red, green or blue, the following pigments mayfurther be used, as the case requires, for fine adjustment of the color.

Orange colorant: C. I. pigment orange 1, 2, 5, 13, 16, 17, 19, 20, 21,22, 23, 24, 34, 36, 38, 39, 43, 46, 48, 49, 61, 62, 64, 65, 67, 68, 69,70, 71, 72, 73, 74, 75, 77, 78, 79

Brown colorant: C. I. pigment brown 1, 6, 11, 22, 23, 24, 25, 27, 29,30, 31, 33, 34, 35, 37, 39, 40, 41, 42, 43, 44, 45

It is, of course, possible to use other colorants such as dyes.

The dyes may, for example, be an azo type dye, an anthraquinone typedye, a phthalocyanine type dye, a quinonimine type dye, a quinoline typedye, a nitro type dye, a carbonyl type dye and a methine dye.

The azo type dye may, for example, be C. I. acid yellow 11, C. I. acidorange 7, C. I. acid red 37, C. I. acid red 180, C. I. acid blue 29, C.I. direct red 28, C. I. direct red 83, C. I. direct yellow 12, C. I.direct orange 26, C. I. direct green 28, C. I. direct green 59, C. I.reactive yellow 2, C. I. reactive red 17, C. I. reactive red 120, C. I.reactive black 5, C. I. disperse orange 5, C. I. disperse red 58, C.

I. disperse blue 165, C. I. basic blue 41, C. I. basic red 18, C. I.mordant red 7, C. I. mordant yellow 5 or C. I. mordant black 7.

The anthraquinone type dye may, for example, be C. I. vat blue 4, C. I.acid blue 40, C. I. acid green 25, C. I. reactive blue 19, C. I.reactive blue 49, C. I. disperse red 60, C. I. disperse blue 56 or C. I.disperse blue 60.

With respect to others, the phthalocyanine type dye may, for example beC. I. pad blue 5; the quinonimine type dye may, for example, be C. I.basic blue 3 or C. I. basic blue 9; the quinoline type dye may, forexample, be C. I. solvent yellow 33, C. I. acid yellow 3 or C. I.disperse yellow 64; and the nitro type dye may, for example, be C. I.acid yellow 1, C. I. acid orange 3 or C. I. disperse yellow 42.

Further, as colorants which may be used for the composition for a colorfilter, inorganic colorants such as barium sulfate, lead sulfate,titanium oxide, yellow lead, iron red, chromium oxide and carbon black,may, for example, be used.

Further, such colorants are preferably used after disperse treatment tohave an average particle diameter of at most 1.0 μm, preferably at most0.5 μm, more preferably at most 0.3 μm.

These colorants are incorporated in a range of usually from 5 to 60 wt%, preferably from 10 to 50 wt %, in the total solid content of thecomposition for a color filter.

(d) Other Components

To the composition for a color filter, a photopolymerization initiator,a thermal polymerization inhibiter, a plasticizer, a storage stabilizer,a surface protecting agent, a smoothing agent, a coating-assisting agentand other additives may further be added, as the case requires.

(d-1) Photopolymerization Initiation System

In a case in which the composition for a color filter comprises anethylenic compound as (b) a monomer, it is necessary to use aphotopolymerization initiation system having a function of directlyabsorbing light or being sensitized with light to induce a decompositionor hydrogen abstraction reaction to generate polymerization-activeradicals.

The photopolymerization initiation system is comprised of a systemcontaining a polymerization initiator and an additive such as anaccelerator. The polymerization initiator may be, for example, a radicalactivator, such as metallocene compounds including titanocene compoundsas described in each of JP-A-59-152396 and JP-A-61-151197, hexaarylbiimidazole derivatives such as 2-(2′-chlorophenyl)-4,5-diphenylimidazol, halomethyl-s-triazine derivatives, N-aryl-α-amino acids suchas N-phenyl glycine, salts of N-aryl-α-amino acids, esters ofN-aryl-α-amino acids, and so on as described in JP-A-10-39503.

The accelerator to be used is, for example, alkyl ester N,N-dialkylaminobenzoate such as ethyl ester N,N-dimethylaminobenzoate, a mercaptocompound having a heterocyclic ring such as 2-mercaptobenzothiazole,2-mercaptobenzoxazole or 2-mercaptobenzoimidazole, an aliphaticpolyfunctional mercapto compound, or the like. Each of thephotopolymerization initiator and the additive may be used incombination of two or more kinds.

The compounding rate of the photopolymerization initiation system is ina range of from 0.1 to 30% by weight, preferably from 0.5 to 20% byweight, more preferably from 0.7 to 10% by weight to the total solidcontent of the composition for the color filter of the presentinvention. If the compounding rate is too low, the sensitivity willbecome lower. On the other hand, if it is too high, the solubility ofunexposed portions in a developer will be degraded, so as to easilyinduce development failure.

(d-2) Thermal Polymerization Inhibitor

The thermal polymerization inhibitor to be used may be, for example,hydroquinone, p-methoxyphenol, pyrogallol, catechol,2,6-t-butyl-p-cresol, β-naphthol, or the like. The compounding rate ofthe thermal polymerization inhibitor is preferably in a range of from 0to 3% by weight to the total solid content of the composition for thecolor filter of the present invention.

(d-3) Plasticizer

The plasticizer to be used may be, for example, dioctyl phthalate,didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycolphthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate,glycerol triacetate, or the like. The compounding rate of theplasticizer is preferably in a range of at most 10% by weight to thetotal solid content of the composition for the color filter of thepresent invention.

(d-4) Sensitizing Dye

Furthermore, for a purpose of improving the sensitivity, a sensitizingdye according to a wavelength of an image exposure light source can bemixed in the composition for a color filter, as the case requires.

Examples of the sensitizing dye include xanthane dyes as described inJP-A-04-221958 and JP-A-04-219756, coumarin dyes having a heterocyclicring as described in JP-A-03-239703 and JP-A-05-289335, 3-ketocoumarincompounds as described in JP-A-03-239703 and JP-A-05-289335,pyrromethene dyes as described in JP-A-06-19240, and dyes having adialkyl aminobenzene skeleton as described in JP-A-47-2528,JP-A-54-155292, JP-B-45-37377, JP-A-48-84183, JP-A-52-112681,JP-A-58-15503, JP-A-60-88005, JP-A-59-56403, JP-A-02-69, JP-A-57-168088,JP-A-05-107761, JP-A-05-210240, and JP-A-04-288818.

Among these sensitizing dyes, preferred is an amino group-containingsensitizing dye, and more preferred is a compound having an amino groupand a phenyl group in the same molecule. Particularly preferred is, forexample, a benzophenone type compound such as4,4′-bis(dimethylamino)benzophenone, 4,4′-bis(diethylamino)benzophenone,2-aminobenzophenone, 4-aminobenzophenone, 4,4′-diaminobenzophenone,3,3′-diaminobenzophenone or 3,4-diaminobenzophenone; ap-dialkylaminophenyl group-containing compound such as2-(p-dimethylaminophenyl)benzoxazole,2-(p-diethylaminophenyl)benzoxazole, 2-(p-dimethylaminophenyl)benzo[4,5]benzoxazole, 2-(p-dimethylaminophenyl)benzo[6,7] benzoxazole,2,5-bis(p-diethylaminophenyl)1,3,4-oxazole,2-(p-dimethylaminophenyl)benzothiazole,2-(p-diethylaminophenyl)benzothiazole,2-(p-dimethylaminophenyl)benzimidazole,2-(p-diethylaminophenyl)benzimidazole,2,5-bis(p-diethylaminophenyl)1,3,4-thiadiazole,(p-dimethylaminophenyl)pyridine, (p-diethylaminophenyl)pyridine,(p-dimethylaminophenyl) quinoline, (p-diethylaminophenyl) quinoline,(p-dimethylaminophenyl)pyrimidine or (p-diethylaminophenyl)pyrimidine;or the like. Among them, most preferred is 4,4′-dialkylaminobezophenone.

The compounding rate of the sensitizing dye is normally in a range offrom 0 to 20% by weight, preferably from 0.2 to 15% by weight, and morepreferably from 0.5 to 10% by weight to the total solid content of thecomposition for a color filter.

(d-5) Other Additives

To the composition for a color filter, an adhesion-improving agent, acoating property-improving agent, a development-improving agent, and soon, may further be optionally added.

The composition for a color filter may be used as dissolved in asolvent, in order to control the viscosity and to dissolve the additivesof the photopolymerization initiation system and others.

The solvent can be optionally selected in accordance with the componentsof the composition such as (a) the binder resin, (b) the monomer, etc.and the solvent may be, for example, diisopropyl ether, mineral spirit,n-pentane, amyl ether, ethyl caprylate, n-hexane, diethyl ether,isoprene, ethyl isobutyl ether, butyl stearate, n-octane, Varsol #2,Apco #18 solvent, diisobutylene, amyl acetate, butyl acetate, Apcothinner, butyl ether, diisobutyl ketone, methyl cyclohexene, methylnonyl ketone, propyl ether, dodecane, Socal solvent No. 1 and No. 2,amyl formate, dihexyl ether, diisopropyl ketone, Solveso #150, (n, sec,t)-butyl acetate, hexene, Shell TS28 solvent, butyl chloride, ethyl amylketone, ethyl benzoate, amyl chloride, ethylene glycol diethyl ether,ethyl orthoformate, methoxymethylpentanone, methyl butyl ketone, methylhexyl ketone, methyl isobutyrate, benzonitrile, ethyl propionate, methylcellosolve acetate, methyl isoamyl ketone, methyl isobutyl ketone,propyl acetate, amyl acetate, amyl formate, bicyclohexyl, diethyleneglycol monoethyl ether acetate, dipentene, methoxymethylpentanol, methylamyl ketone, methyl isopropyl ketone, propyl propionate, propyleneglycol-t-butyl ether, methyl ethyl ketone, methyl cellosolve, ethylcellosolve, ethyl cellosolve acetate, carbitol, cyclohexanone, ethylacetate, propylene glycol, propylene glycol monomethyl ether, propyleneglycol monomethyl ether acetate, propylene glycol monoethyl ether,propylene glycol monoethyl ether acetate, dipropylene glycol monoethylether, dipropylene glycol monomethyl ether, dipropylene glycolmonomethyl ether acetate, 3-methoxypropionic acid, 3-ethoxypropionicacid, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl3-methoxypropionate, ethyl 3-methoxypropionate, propyl3-methoxypropionate, butyl 3-methoxypropionate, diglyme, ethylene glycolacetate, ethylcarbitol, butylcarbitol, ethylene glycol monobutyl ether,propylene glycol-t-butyl ether, 3-methyl-3-methoxybutanol, tripropyleneglycol methyl ether, 3-methyl-3-methoxybutyl acetate, or the like. Thesesolvents may be used in combination of two or more.

The solid content concentration in the composition for a color filter isselected in accordance with a coating method to be applied. In a spincoat, a slit and spin coat, and a die coat widely used in the productionof the color filter at present, an appropriate solid content is normallyin a range of from 1 to 40% by weight and preferably in a range of from5 to 30% by weight.

A combination of solvents is determined taking a dispersion stability ofa pigment, a solubility to soluble components in the solid contents,such as the resin, monomer and photopolymerization initiator, a dryingproperty in coating, and a drying property in a reduced-pressure dryingstep into consideration.

A composition for a color filter using the above compounded componentsis produced, for example, as follows.

First, a colorant is subjected to a dispersion treatment and controlledinto a state of ink. The dispersion treatment is conducted by means of apaint conditioner, a sand grinder, a ball mill, a roll mill, a stonemill, a jet mill, a homogenizer or the like. The colorant is broughtinto a state of fine particles by the dispersion treatment, therebyachieving an improvement in transmittance of transmitted light and animprovement in a coating property.

The dispersion treatment is preferably conducted in such a system that abinder resin having a dispersing function, a dispersing agent such as asurfactant, a dispersing assistance, etc. are optionally used togetherwith the colorant and the solvent. It is particularly preferable to usea polymer dispersing agent, by virtue of its excellent dispersionstability over time.

For example, when the dispersion treatment is conducted by use of thesand grinder, it is preferred to use glass beads or zirconia beadshaving a particle size of from 0.05 to several millimeters. Atemperature in the dispersion treatment is normally set in a range offrom 0° C. to 100° C., preferably from room temperature to 80° C. Adispersing time is appropriately adjusted because an appropriate timefor the dispersion treatment varies depending on the composition of ink(the colorant, the solvent and the dispersing agent), instrumentspecifications of the sand grinder, and so on.

Then the binder resin, monomer, photopolymerization initiation system,and others are mixed into the color ink obtained by the above dispersiontreatment, to form a uniform solution. Since fine foreign particles areoften mixed into the solution in each of the dispersion treatment stepand the mixing step, the resulting solution is preferably filtered bymeans of a filter or the like.

(4-4) Other Constructions

The color image display device preferably has an absorbing sectioncontaining an absorbent to absorb ultraviolet to near ultraviolet lightemitted from the semiconductor light emitting device. It may be providedon the panel portion to display an image or on the backlight. In a casewhere the absorbing section is provided on the panel portion, theabsorbing section may be disposed, for example, at one or more positionsamong between the light diffusion sheet 3 and the polarizer 4, betweenthe polarizer 4 and the glass substrate 5, between the glass substrate 8and the polarizer 10 and on the surface of the polarizer 10, in FIG. 1.Whereas, in a case where the absorbing section is provided on thebacklight, the absorbing section may be disposed, for example, at one ormore positions among between the light source 1 and the light guide 11,between the light guide 11 and the light control sheet 13 and on thesurface of the light control sheet 13, in FIGS. 3 and 4.

In either case of providing the absorbing section on the panel portionor on the backlight, the absorbing section may be provided in the formof a sheet or a coating film formed of a resin containing the absorbent,or may be provided by incorporating the absorbent in the above-mentionedcomponent.

By providing the absorbing section in the color image display device asdescribed above, it is possible to suppress an influence of theultraviolet to near ultraviolet light over various componentsconstituting the color image display device or to the observer. From theviewpoint of suppressing the influence to the observer, the position toform the absorbing section is optional, but from the viewpoint ofsuppressing the influence over the components constituting the colorimage display device, it is preferred to provide the absorbing sectionon the side as near as possible to the semiconductor light emittingdevice in the traveling direction of light from the semiconductor lightemitting device. Especially with a view to suppressing deterioration ofthe color filter or liquid crystal by the ultraviolet or nearultraviolet light, it is preferred to provide the absorbing sectionbefore the liquid crystal in the traveling direction of the light fromthe semiconductor light emitting device.

Here, the absorbent contained in the absorbing section will be describedin detail. The absorbent to be used in the present invention is notparticularly limited so long as it has a function to absorb theultraviolet to near ultraviolet light. It may, for example, be abenzophenone type absorbent such as o-hydroxybenzophenone,2-hydroxy-4-n-octoxybenzophenone or 2-hydroxy-4-methoxybenzophenone; abenzotriazole type absorbent such as 2-(2′-hydroxyphenyl)benzotriazole,2-(2′-hydroxy-5′-t-octylphenyl)benzotriazole,2-(2′-hydroxy-3′-t-butyl-5′-methylphenyl)-5-chlorobenzotriazole or2-(2′-hydroxy-5′-methylphenyl)benzotriazole; a cyano acrylate typeabsorbent such as ethyl-2-cyano-3,3-diphenyl acrylate or5-ethylhexyl-2-cyano-3,3-diphenyl acrylate; a salicylate type absorbentsuch as phenyl salicylate or 4-t-butylphenyl salicylate; an oxalic acidanilide type absorbent such as2-ethyl-5′-t-butyl-2′-ethoxy-N,N′-diphenyloxalamide; or an inorganicoxide type absorbent such as zinc oxide, titanium oxide or zirconiumoxide. Here, these inorganic oxides may be used as contained in glass toform an ultraviolet-shielding glass.

The absorbent can be used as dissolved in a resin, whereby thetransparency is good. Further, as an inorganic adsorbent, dispersedparticles having an average particle size of at most 100 nm may be usedso that an absorbing section excellent in transparency may be obtained.Further, in the case of an optically active compound such as titaniumoxide, it is preferred that the particle surface is treated with aninert material such as silica. With such an absorbent, theultraviolet-shielding effect may be adjusted by adjusting its amountadded to the resin. Among them, as an absorbent to shield an ultravioletray of at most 350 nm, a benzophenone type or zinc oxide type absorbentmay be mentioned. They may be used alone or in combination as a mixtureof two or more of them. By using these absorbents, it is possible tosubstantially shield light with a wavelength of at most 350 nm. In orderto further prevent deterioration of the organic compound such as abinder resin and to improve the durability of the color image displaydevice, it is preferred to shield near ultraviolet light having awavelength of at most 400 nm, and such can be accomplished by suitablyselecting the absorbent among the above-described ones.

The absorbent is used usually as mixed with a suitable resin. The resinto be used for this purpose may, for example, be a thermoplastic resin,a thermosetting resin or a photocurable resin. Specifically, it may, forexample, be an acrylic resin such as polymethyl methacrylate; a styreneresin such as polystyrene or a styrene/acrylonitrile copolymer; apolycarbonate resin; a polyester resin; a phenoxy resin; a butyralresin; a polyvinyl alcohol; a cellulose resin such as ethyl cellulose,cellulose acetate or cellulose acetate butyrate; an epoxy resin; aphenol resin; or a silicone resin. Among them, an epoxy resin, a butyralresin or a polyvinyl alcohol, may, for example, be preferred from theviewpoint of the transparency, heat resistance, light resistanttoughness, etc.

EXAMPLES

Now, the present invention will be described in further detail withreference to Examples, but it should be understood that the presentinvention is by no means restricted to the following Examples.

Group I of Examples Production of Light Emitting Device and Color ImageDisplay Device

In the following Examples, “parts” means “parts by weight”.

(1) Preparation of Phosphors (1-1) Preparation Example 1: Red EmittingPhosphor K₂Tif₆:Mn (Hereinafter Sometimes Referred to Also as “KTF”)

So that the feedstock composition for a phosphor would be K₂ Ti_(0.95)Mn_(0.05) F₆, as raw material compounds, K₂ TiF₆ (4.743 g) and K₂ MnF₆(0.2596 g) were slowly added and dissolved in 40 ml of hydrofluoric acid(47.3 wt %) with stirring under atmospheric pressure at roomtemperature. After the respective raw material compounds were alldissolved, 60 ml of acetone was added at a rate of 240 ml/hr whilestirring the solution to let a phosphor precipitate in the poor solvent.The obtained phosphor was washed with pure water and acetone,respectively, followed by drying at 100° C. for one hour. The obtainedphosphor was confirmed to be K₂ TiF₆:Mn by X-ray diffraction pattern.

(1-2) Preparation Example I-2: Green Emitting Phosphor Ba₃Si₆O₁₂N₂:Eu(Hereinafter Sometimes Referred to as “BSON”)

So that the feedstock composition for a phosphor would be Ba_(2.7)Eu_(0.3) Si_(6.9) O₁₂ N_(3.2), as raw material compounds, BaCO₃ (267 g),SiO₂ (136 g) and Eu₂O₃ (26.5 g) were thoroughly stirred and mixed, andthen filled in an alumina mortar. This mortar was placed in a resistanceheating type electric furnace equipped with a temperature adjuster,heated to 1,100° C. at a temperature raising rate of 5° C./min underatmospheric pressure, held at that temperature for 5 hours and then leftto cool to room temperature. The obtained sample was pulverized to atmost 100 μm in the alumina mortar.

The obtained sample (295 g) and Si₃ N₄ (45 g) as a raw material compoundwere thoroughly stirred and mixed, and then filled in an alumina mortarfor primary firing, and this mortar was heated to 1,200° C. underatmospheric pressure while circulating a gas mixture of 96 vol % ofnitrogen and 4 vol % of hydrogen at a rate of 0.5 L/min, held at thattemperature for 5 hours and then left to cool to room temperature. Theobtained fired powder was pulverized to at most 100 μm in the aluminamortar.

300 g of the fired powder obtained in the above primary firing, and asflux BaF₂ (6 g) and BaHPO₄ (6 g) were thoroughly stirred and mixed, thenfilled in an alumina mortar, heated to 1,350° C. under atmosphericpressure while circulating a gas mixture of 96 vol % of nitrogen and 4vol % of hydrogen at a rate of 0.5 L/min as secondary firing, held atthat temperature for 8 hours and then left to cool to room temperature.The obtained fired powder was pulverized to at most 100 μm in thealumina mortar.

A sample (70 g) obtained by the above secondary firing, BaCl₂ (5.6 g) asflux and BaHPO₄ (3.5 g) were thoroughly stirred and mixed, then filledin an alumina mortar, heated to 1,200° C. under atmospheric pressurewhile circulating a gas mixture of 96 vol % of nitrogen and 4 vol % ofhydrogen at a rate of 0.5 L/min as third firing, held at thattemperature for 5 hours and then left to cool to room temperature. Theobtained fired powder was slurried and dispersed by means of glassbeads, sieved to separate particles of at most 100 μm, then subjected towashing treatment, followed by surface coating by calcium phosphate bymeans of a calcium solution and a phosphate solution.

2 g of the obtained phosphor was heated in an atmospheric air to 700° C.in about 40 minutes by means of a quartz container having a diameter of30 mm, and held at 700° C. for 10 minutes and then the quartz containerwas taken out from the furnace and cooled to room temperature on a heatresistant brick. From an X-ray diffraction pattern of the obtained firedproduct, it was confirmed that Ba₃Si₆O₁₂N₂:Eu was prepared.

(1-3) Preparation Example I-3: Green Emitting Phosphor Eu-Activatedβ-SiAlON Phosphor (hereinafter sometimes referred to as “(β-SiAlON”)

95.5 wt % of α-silicon nitride powder, 3.3 wt % of aluminum nitridepowder, 0.4 wt % of aluminum oxide powder and 0.8 wt % of europium oxidepowder were thoroughly mixed in an agate mortar, and this raw materialpowder was filled in a crucible made of boron nitride and subjected toheat treatment at 1,950° C. for 12 hours in a pressurized nitrogenatmosphere of 0.92 MPa in a pressure nitriding furnace having a carbonheater. The obtained fired powder was pulverized, then sieved, subjectedto washing treatment and then dried to obtain a phosphor powder. By thepowder X-ray diffraction measurement, the prepared powder was found tobe a single phase Eu-activated β-sialon phosphor.

(1-4) Preparation Example I-4: Red Emitting Phosphor BaTiF₆:Mn(Hereinafter Sometimes Referred to as “BTF”)

So that the feedstock composition for a phosphor would be K₂ Ti_(0.95)Mn_(0.05) F₆, as raw material compounds, K₂ TiF₆ (4.743 g) and K₂ MnF₆(0.2569 g) were slowly added and dissolved in 50 ml of hydrofluoric acid(47.3 wt %) with stirring under atmospheric pressure at roomtemperature. After the respective raw material compounds were alldissolved, BaCO₃ (3.8987 g) was added to a solution while stirring thesolution to let the phosphor BaTiF₆:Mn precipitate. The obtainedphosphor was washed with pure water and acetone, respectively, and driedat 100° C. for one hour.

(1-5) Preparation Example I-5: Red Emitting Phosphor K₂SiF₆:Mn(Hereinafter Sometimes Referred to as “KSF”)

So that the feedstock composition for a phosphor would be K₂ Si_(0.9)Mn_(0.1) F₆, as raw material compounds, K₂ SiF₆ (1.7783 g) and K₂ MnF₆(0.2217 g) were added and dissolved in 70 ml of hydrofluoric acid (47.3wt %) with stirring under atmospheric pressure at room temperature.After the respective raw material compounds were all dissolved, 70 ml ofacetone was added at a rate of 240 ml/hr while stirring the solution tolet a phosphor precipitate in the poor solvent. The obtained phosphorwas washed with ethanol and dried at 130° C. for one hour to obtain 1.7g of the phosphor.

From the X-ray diffraction pattern of the obtained phosphor, it wasconfirmed that K₂SiF₆:Mn was prepared.

(1-6) Preparation Example I-6: Green Emitting Phosphor BaMgAl₁₀O₁₇:Eu,Mn(Hereinafter Sometimes Referred to as “GBAM”)

As phosphor raw materials, barium carbonate (BaCO₃), europium oxide(Eu₂O₃), basic magnesium carbonate (mass per mol of Mg: 93.17),manganese carbonate (MnCO₃) and α-alumina (Al₂ O₃), and, as a firingassistant, aluminum fluoride (AlF₃) were used. These phosphor rawmaterials were weighed in such amounts that the chemical compositionwould be Ba_(0.455) Sr_(0.245) EU_(0.3) Mg_(0.7) Mn_(0.3) Al₁₀ O₁₇, andthe firing assistant was weighed in an amount of 0.8 wt % to the totalweight of the phosphor raw materials, and they were mixed in a mortarfor 30 minutes and then filled in an alumina crucible. In order toproduce a reducing atmosphere for firing, alumina crucibles weredoubled, and graphite beads were packed in a space surrounding theinside crucible, followed by firing at 1,550° C. for two hours in theatmosphere. The obtained fired product was pulverized to obtain a greenemitting phosphor (GBAM).

(1-7) Preparation Example I-7: Blue Emitting Phosphor Sr₁₀(PO₄)₆Cl₂:Eu(Hereinafter Referred to as “SCA”)

0.2 mol of SrCO₃ (manufactured by Kanto Chemical Co., Inc.), 0.605 molof SrHPO₄ (manufactured by Kanto Chemical Co., Inc.), 0.050 mol of Eu₂O₃ (manufactured by Shin-Etsu Chemical Co., Ltd., purity: 99.99%) and0.1 mol of SrCl₂ (manufactured by Kanto Chemical Co., Inc.) were weighedand dry-mixed by a small size V-type blender.

The obtained raw material mixture was filled in an alumina crucible andset in a box type electric furnace. The temperature was raised to 1,050°C. at a temperature raising rate of 5° C./min in the atmosphere underatmospheric pressure, and maintained for 5 hours to obtain a firedproduct (primary firing).

Then, the crucible was cooled to room temperature, and the content ofthe crucible was taken out and pulverized.

To the obtained fired product, 0.05 mol of SrCl₂ was added, and themixture was mixed in a small size V-type blender and then filled in analumina crucible. The crucible was set in the same electric furnace asfor the primary firing. While circulating a hydrogen-containing nitrogengas (hydrogen:nitrogen=4:96 by volume ratio) at a rate of 2.5 l/min, thetemperature was raised to 950° C. at a temperature raising rate of 5°C./min in a reducing atmosphere under atmospheric pressure andmaintained for 3 hours (secondary firing). Then, the crucible was cooledto room temperature, and the content of the crucible was taken out andpulverized. To the obtained fired product, 0.05 mol of SrCl₂ was added,and the mixture was mixed in a small size V-type blender and then filledin an alumina crucible. Again, the crucible was set in the same electricfurnace as for the secondary firing. While circulating ahydrogen-containing nitrogen gas (hydrogen:nitrogen=4:96 by volumeratio) at a rate of 2.5 l/min, the temperature was raised to 1,050° C.at a temperature raising rate of 5° C./min in a reducing atmosphereunder atmospheric pressure and maintained for 3 hours.

The obtained fired product was roughly pulverized to a particle size ofabout 5 mm and then treated by a ball mill for 6 hours to obtain aphosphor slurry.

To wash the phosphor, the phosphor slurry was stirred and mixed with alarge amount of water and left to stand until the phosphor particlessettled, and then the supernatant was discarded. This operation wasrepeated until the electrical conductivity of the supernatant became atmost 3 mS/m. After confirming that the electrical conductivity of thesupernatant became at most 3 mS/m, classification was carried out toremove fine particles and coarse particles of the phosphor.

The obtained phosphor slurry was dispersed in a Na₃ PO₄ aqueous solutionwith pH=10, and after removing small particles by classification,calcium phosphate treatment was carried out. After dehydration, dryingwas carried out at 150° C. for 10 hours to obtain a phosphor(SCA):Sr₁₀(PO₄)₆Cl₂:Eu. When the obtained phosphor was excited by lightwith a wavelength of 400 nm, the emission peak wavelength was 450 nm,and the half-value width was 29 nm.

(1-8) Evaluation of Temperature Dependency of Phosphor

With respect to the respective phosphors prepared in the above (1-1) to(1-6) and a red emitting phosphor “BR-101B” (CaAlSiN₃:Eu, hereinaftersometimes referred to as “CASN660”) manufactured by Mitsubishi ChemicalCorporation, the temperature dependency of the luminance and emissionpeak intensity (hereinafter sometimes generally referred to as“temperature characteristics”) under excitation with wavelengths of 400nm and 455 nm, were measured.

The measurement of the temperature characteristics was carried out bythe following procedure by using an apparatus equipped with MCPD7000multichannel spectrum-measuring device manufactured by Otsuka ElectricsCo., Ltd. as an emission spectrum-measuring device, Luminancecalorimeter BM5A as a luminance-measuring device, a stage provided witha cooling mechanism by a Peltier element and a heating mechanism by aheater, and a 150 W xenon lamp as a light source.

A cell containing a phosphor sample was placed on the stage, and thetemperature was changed from 25° C. to 150° C., whereby the surfacetemperature of the phosphor was confirmed, and then, the phosphor wasexcited by light having a wavelength of 400 nm or 455 nmspectroscopically taken out from a light source by means of adiffraction grating, to measure the emission spectrum. From the measuredemission spectrum, the emission peak intensity at 25° C. and theemission peak intensity at 100° C. were obtained, and the variation rate(%) of the emission peak intensity was obtained by the following formula(A).

{1−(emission peak intensity at 100° C.)/(emission peak intensity at 25°C.)}×100  (A)

Here, as the measured value of the surface temperature of the phosphoron the side irradiated with the excitation light, a value corrected byusing the temperature values measured by a radiation thermometer and athermocouple, was used. The results are shown in the following Table 10.

With respect to SCA i.e. the blue emitting phosphor prepared in theabove (1-7), the temperature characteristics were measured underexcitation with a wavelength of 400 nm, whereby the variation rate ofthe emission peak intensity was 14%.

TABLE 10 Emission Wavelength Variation rate Red peak range of ofemission emitting wavelength Half-value excitation peak intensityphosphor Type (nm) width (nm) light (nm) (%) Notes Preparation KTF 631 7320-520 20 455 nm Example I-1 excitation Preparation BTF 632 7 335-52040 455 nm Example I-4 excitation Preparation KSF 630 6 310-510 15 455 nmExample I-5 excitation CASN660 659 89 300-620 10 400 nm excitationEmission Variation rate Green peak Emission of emission emittingwavelength Half-value wavelength peak intensity phosphor Type (nm) width(nm) range (nm) (%) Notes Preparation BSON 529 68 470-610 17 455 nmExample I-2 excitation Preparation β-SiAlON 542 56 495-620 12 455 nmExample I-3 excitation Preparation GBAM 517 27 495-560 9 400 nm ExampleI-6 excitation

(2) Production of Backlight

Production Examples of the backlight of the present invention will begiven.

(2-1) Production Example I-1: Production of Backlight 1 (BL-1)

A light-emitting device is prepared by the following procedure.

A blue light emitting diode having a peak emission wavelength of 454 nmis bonded to a cup bottom surface of a frame by die bonding, and then,the light emitting diode and the frame electrodes are connected by wirebonding.

As a green-emitting phosphor, BSON is used, and as a red-emittingphosphor, KTF is used. These phosphors are kneaded into a silicone resin“JCR6101UP” manufactured by Dow Corning Toray Silicone Co., Ltd. toobtain a paste, which is applied and cured on the light emitting diodein the cup to obtain a semiconductor light emitting device.

Then, a cyclic polyolefin type resin sheet (trade name “ZEONOR”manufactured by ZEON CORPORATION) of wedge shape, which has a size of289.6×216.8 mm and a thicknesses varying along the direction of theshort side between a maximum thickness of 2.0 mm and a minimum thicknessof 0.6 mm, is used as a light guide, and a semiconductor light emittingdevice (light source) comprised of the above-mentioned light emittingdiode is placed along the thick long side, so as to allow emitted lightfrom the linear light source to efficiently enter the thick side (lightentrance surface) of the light guide.

The surface opposite to the light exit surface of the light guide ispatterned by transferring fine circular patterns of rough surfaces withgradually increasing diameter according to the distance from the linearlight source, from a die to the surface. The diameter of the roughsurface patterns is 130 μm near the light source, gradually increaseswith distance from the light source, and is 230 μm at the most distantposition.

The die used in the formation of the fine circular patterns of the roughsurfaces herein is prepared by laminating a dry film resist in athickness of 50 μm on a SUS substrate, forming openings in portionscorresponding to the patterns by photolithography, further subjectingthe die to uniform blasting under a projection pressure of 0.3 MPa withspherical glass beads of #600 by a sandblasting method, and thereafterpeeling the dry film resist off.

The light exit surface of the light guide is provided with a triangularprism array with the apex angle of 90° and the pitch of 50 μm so thatthe ridge lines are approximately perpendicular to the light entrancesurface of the light guide, thus achieving a structure of enhancing alight collecting property of beams emitted from the light guide. A dieused in the formation of the light collecting element array consistingof the triangular prism array is prepared by a process of cutting astainless steel substrate overlaid with an M nickel coating byelectroless plating, with a single-crystal diamond cutting tool.

A light reflecting sheet (“Lumirror E60L” manufactured by TORAYIndustries, Inc.) is placed on the side opposite to the light exitsurface of the light guide, a light diffuser sheet is placed on thelight exit surface, and two sheets with a triangular prism array havingthe apex angle of 90° and the pitch of 50 μm (“BEFIII” manufactured bySUMITOMO 3M Limited) are placed on the light diffuser sheet so that theridge lines of the respective two prism sheets become perpendicular toeach other, thereby obtaining a backlight 1 (BL-1).

The backlight 1 (BL-1) thus obtained has one emission peak wavelength ineach of the wavelength regions of 455 nm, 529 nm and 631 nm.

(2-2) Production Example I-2: Production of Backlight 2 (BL-2)

A backlight 2 (BL-2) is prepared in the same manner as in ProductionExample I-1 except that in Production Example I-1,8-SiAlON is usedinstead of BSON as a green emitting phosphor. The backlight 2 has oneemission peak wavelength in each of the wavelength regions of 455 nm,542 nm and 631 nm.

(2-3) Production Example I-3: Production of Backlight 3 (BL-3)

A backlight 3(BL-3) is prepared in the same manner as in ProductionExample I-1 except that in Production Example I-1, BaTiF₆:Mn is usedinstead of KTF as a red emitting phosphor. Here, BaTiF₆:Mn is a phosphordisclosed in US2006/0169998A1, and its emission spectrum is disclosed inthe same document. As shown in the same document, the backlight 3 hasone emission peak wavelength in each of the wavelength regions of 455nm, 529 nm and 631 nm.

(2-4) Production Example I-4: Production of Backlight 4 (BL-4)

A backlight 4(BL-4) is prepared in the same manner as in ProductionExample I-1 except that in Production Example I-1, as a green emittingphosphor, β-SiAlON is used, instead of BSON. The backlight 4 has oneemission peak wavelength in each of the wavelength regions of 456 nm,542 nm and 631 nm.

(2-5) Production Example I-5: Production of Conventional Backlight 5(BL-5) as Comparative Example

A light emitting device is prepared by the following procedure.

A blue color emitting diode having a peak emission wavelength of 460 nmis bonded to a cup bottom surface of a frame by die bonding, and then,the light emitting diode and frame electrodes are connected by wirebonding. As a yellow emitting phosphor, Y_(2.8)Tb_(0.1)Ce_(0.1)Al₅O₁₂ isprepared in accordance with the method disclosed in Example 1 ofJP-A-2006-265542 and is used. This phosphor is kneaded to an epoxy resinto obtain a paste, which is applied and cured on the light emittingdiode in the cup. For the subsequent process, the same method as inPreparation Example I-1 is used to obtain a conventional backlight 5 asComparative Example.

(2-6) Production Example I-6

Production of Backlight 6 (BL-6)

As a near ultraviolet emitting LED to emit a dominant emissionwavelength of from 390 nm to 400 nm, 290 μm square chip C395 MB290manufactured by Cree was used, and it was bonded to terminals at thebottom of a concave portion of a 3528SMD type PPA resin package by asilicone resin base transparent die bonding paste. Then, heating wascarried out at 150° C. for two hours to cure the transparent die bondingpaste, and then the near ultraviolet LED and the electrodes of thepackage were wire-bonded by using a gold wire having a diameter of 25μm.

On the other hand, KSF prepared in Preparation Example I-5 for phosphor,GBAM prepared in Preparation Example I-6 and the SCA phosphor preparedin Preparation Example I-7 are used, and as binder resins, a siliconeresin (SCR1011) manufactured by Shin-Etsu Chemical Co., Ltd. and AEROSIL(RX200) manufactured by Nippon Aerosil Co., Ltd. were weighed in theblend amounts as disclosed in Table 11, followed by mixing by anagitation defoaming device AR-100 manufactured by Thinky Corporation toobtain a phosphor-containing composition.

Then, using a dispenser, 4 μl of the phosphor-containing compositionobtained as described above was injected into a concave portion of theSMD type resin package having the above near ultraviolet emitting LEDmounted. Then, heating was carried out at 70° C. for one hour and thenat 150° C. for 5 hours to cure the phosphor-containing compositionthereby to prepare a backlight 6 (BL-6).

(2-7) Production Example I-7: Production of Backlight 7 (BL-7) forComparative Example

A backlight 7 (BL-7) is prepared in the same manner as in ProductionExample I-6 except that the red emitting phosphor to be used is changedto CASN660 having a long wavelength as the emission peak wavelength anda wide half-value width, and the amounts of the respective phosphors,the silicone resin and the AEROSIL are changed as shown in Table 11.

(2-8) Production Example I-8: Production of Backlight 8 (BL-8)

A backlight 8 (BL-8) is prepared in the same manner as in ProductionExample I-6 except that the amounts of the respective phosphors, thesilicone resin and the AEROSIL are changed as shown in Table 11.

(2-9) Production Example I-9: Production of Backlight 9 (BL-9) forComparative Example

A backlight 9 (BL-9) is prepared in the same manner as in ProductionExample I-6 except that the red emitting phosphor to be used is changedto CASN660 having a long wavelength as the emission peak wavelength anda wide half-value width, and the amounts of the respective phosphors,the silicone resin and the AEROSIL are changed as shown in Table 11.

TABLE 11 Blend amounts (g) Blue emitting Green emitting Red emittingSilicone phosphor phosphor phosphor resin AEROSIL BL-7 SCA 0.030 GBAM0.091 CASN660 0.010 0.610 0.019 BL-6 SCA 0.053 GBAM 0.088 KSF 0.3040.793 0.025 BL-9 SCA 0.040 GBAM 0.090 CASN660 0.009 0.606 0.019 BL-8 SCA0.040 GBAM 0.065 KSF 0.150 0.602 0.019

(3) Production of Binder Resins (3-1) Production Example I-10: BinderResin A 55 Parts by weight of benzyl methacrylate, 45 parts by weight ofmethacrylic acid and 150 parts by weight of propylene glycol monomethylether acetate are put into a 500 ml separable flask, and the interior ofthe flask is sufficiently replaced with nitrogen. Thereafter, 6 parts byweight of 2,2′-azobisisobutyronitrile is added, followed by stirring at80° C. for 5 hours to obtain a polymer solution. The prepared polymerhas a weight average molecular weight of 8,000 and an acid value of 176mgKOH/g. (3-2) Production Example I-11: Binder Resin B

145 parts by weight of propylene glycol monomethyl ether acetate isstirred while carrying out replacement with nitrogen, and thetemperature is raised to 120° C. Then, 20 parts by weight of styrene, 57parts of glycidyl methacrylate and 82 parts by weight of a monoacrylatehaving a tricyclodecane skeleton (FA-513M, manufactured by HitachiChemical Company, Ltd.) are dropwise added, followed by further stirringat 120° C. for two hours.

Then, the interior of the reactor is replaced with air, 27 parts byweight of acrylic acid, 0.7 part by weight oftrisdimethylaminomethylphenol and 0.12 part by weight of hydroquinoneare introduced, and the reaction is continued at 120° C. for 6 hours.Thereafter, 52 parts by weight of tetrahydrophthalic anhydride (THPA)and 0.7 part by weight of triethylamine are added, followed by areaction at 120° C. for 3.5 hours.

The polymer thus obtained has a weight average molecular weight Mw ofabout 8,000.

(4) Production Example I-12: Production of Clear Resist Solution

A resist solution is obtained by mixing the following components in thefollowing proportions and stirring the components with a stirrer untilthe components are completely dissolved.

Binder Resin B Prepared in Production Example I-11: 2.0 Parts

Dipentaerythritol hexaacrylate: 1.0 part

Photopolymerization initiation system

-   -   2-(2′-chlorophenyl)-4,5-diphenylimidazole: 0.06 part    -   2-mercaptobenzothiazole: 0.02 part    -   4,4′-bis(diethylamino)benzophenone: 0.04 part

Solvent (propylene glycol monomethyl ether acetate): 9.36 parts

Surfactant (“F-475” manufactured by Dainippon Ink and Chemicals,Incorporated): 0.0003 part

(5) Production of Color Filter (5-1) Production Example I-13: Productionof Red Pixels (for Examples I-1 to 10 and Comparative Examples I-1 to 4)

75 parts of propylene glycol monomethyl ether acetate, 16.7 parts of ared pigment (hereinafter referred to as “P.R.”) 254, 4.2 parts ofacrylic dispersant “DB2000” manufactured by Big Chemie and 5.6 parts ofbinder resin A prepared in Production Example I-10 are mixed and stirredwith a stirrer for three hours to prepare a mill base having a solidcontent concentration of 25% by weight. This mill base was subjected toa dispersion treatment at a peripheral velocity of 10 m/s for aresidence time of three hours with a bead mill system using 600 parts of0.5-mmφ zirconia beads, thereby to obtain a P.R.254 dispersed ink.

Another mill base is prepared in the same composition as in the aboveP.R.254 case except for a change of the pigment to an azo nickel complexyellow pigment prepared in accordance with the disclosure of ProductionExample of Example 2 (paragraph [0066]) of JP-A-2007-25687, and issubjected to a dispersion treatment under similar dispersion conditionsfor a residence time of two hours, thereby to obtain an azo nickelcomplex yellow pigment-dispersed ink as disclosed in JP-A-2007-25687.Further, another mill base is prepared in the same composition as in theabove P.R.254 except for a change of the pigment to P.R.177, and issubjected to a dispersion treatment under similar dispersion conditionsfor a residence time of three hours, thereby to obtain a P.R.177dispersed ink.

The dispersed inks obtainable as described above and the resist solutionobtainable in the above Production Example I-12 are mixed and stirred inthe compounding ratio as shown in the following Table 12, and a solvent(propylene glycol monomethyl ether acetate) is added thereto to bringthe final solid content concentration to be 25 wt %, thereby to obtain acomposition for a red color filter.

The composition for a color filter thus obtained is applied on a glasssubstrate of 10 cm×10 cm (“AN635” manufactured by Asahi Glass Company,Limited) by a spin coater, and dried. The entire surface of thissubstrate is irradiated with ultraviolet light with an exposure amountof 100 mJ/cm², followed by development with an alkali developer and thenby post-baking in an oven at 230° C. for 30 minutes, thereby to preparea red pixel sample for measurement. The thickness of the red pixel afterthe preparation is adjusted to be 2.5 μm.

TABLE 12 Azo nickel R254 R177 complex Clear resist For Ex. I-1, 3, 518.5 10.7 0 70.8 and 7 For Ex. I-2, 4, 6, 8 24.1 13.9 0 62.0 to 10 andComp. Ex. I-3 and 4 For Comp. Ex. I-1 16.4 6.3 0 77.3 For Comp. Ex. I-216.7 17.2 0 66.1

(5-2) Production Example I-14: Production of Green Pixels (for ExamplesI-1 to 10, and Comparative Examples I-1 to 4)

A mill base is prepared in the same composition as in the P.R.254 casein Production Example I-13 except for a change of the pigment to pigmentgreen (hereinafter referred to as “P.G.”) 36, and is subjected to adispersion treatment under similar dispersion conditions for a residencetime of one hour, thereby to obtain a P.G.36 dispersed ink.

A P.G.7 dispersed ink is prepared in the same manner as above except forchanging the pigment to pigment green (hereinafter referred to as“P.G.”) 7.

Here, the azo nickel complex yellow pigment-dispersed ink disclosed inJP-A-2007-25687 is prepared in the same manner as disclosed inProduction Example I-13.

Similarly, a mill base is prepared in the same composition except for achange of the pigment to zinc phthalocyanine bromide and the dispersantto the acrylic dispersant “LPN6919” manufactured by Big Chemie andsubjected to dispersion treatment under the same dispersion conditionsfor a residence time of 3 hours thereby to obtain a zinc phthalocyaninebromide-dispersed ink. Here, the zinc phthalocyanine bromide pigment wasprepared by the method shown in the following (5-2-1).

(5-2-1) Preparation Example for Zinc Phthalocyanine Bromide

Zinc phthalocyanine was prepared by using phthalodinitrile and zincchloride as raw materials. Its 1-chloronaphthalene solution hadabsorption of light at from 600 to 700 nm. The halogenation was carriedout by mixing 3.1 parts of furfuryl chloride, 3.7 parts of anhydrousaluminum chloride, 0.46 part of sodium chloride and 1 part of zincphthalocyanine and dropwise adding 4.4 parts of bromine. The reactionwas carried out at 80° C. for 15 hours, and then, the reaction mixturewas put into water to let zinc phthalocyanine bromide crude pigmentprecipitate. This aqueous slurry was subjected to filtration and washingwith hot water of 80° C., followed by drying at 90° C. to obtain 3.0parts of a refined zinc phthalocyanine bromide crude pigment.

One part of this zinc phthalocyanine bromide crude pigment, 12 parts ofpulverized sodium chloride, 1.8 parts of diethylene glycol and 0.09 partof xylene were charged into a dual-armed kneader and kneaded at 100° C.for 6 hours. After the kneading, the mixture was taken into 100 parts ofwater at 80° C., followed by stirring for one hour and then byfiltration, washing with hot water, drying and pulverization to obtain azinc phthalocyanine bromide pigment. The obtained zinc phthalocyaninebromide pigment was found to have an average composition of ZnPcBr₁₄ Cl₂(where Pc: phthalocyanine) and contains 14 bromine atoms per molecule onaverage, from the analysis of the halogen content by mass analysis.Further, the average value of the primary particle size measured by atransmission electron microscope (H-9000UHR, manufactured by Hitachi,Ltd.) was 0.023 μm. Here, the average primary particle size of thepigment was obtained in such a manner that the pigment was dispersed inchloroform by ultrasonic waves and dropped on a collodionmembrane-bonded mesh and dried, followed by observation by atransmission electron microscope (TEM) to obtain an image of primaryparticles of the pigment, and from this image, the primary particlesizes were measured, and the average particle size was obtained.

A dispersed ink obtained as described above, and a resist solutionprepared in the above Production Example I-12 are mixed and stirred in ablend ratio as shown in the following Table 13, and a solvent (propyleneglycol monomethyl ether acetate) is added so that the final solidcontent concentration will be 25 wt % thereby to obtain a compositionfor a green color filter.

The composition for a color filter thus obtained is applied on a glasssubstrate of 10 cm×10 cm (“AN635”, manufactured by Asahi Glass Company,Limited) by a spin coater, and dried. The entire surface of thissubstrate is irradiated with ultraviolet light with an exposure amountof 100 mJ/cm², followed by development with an alkali developer and thenby post-baking in an oven at 230° C. for 30 minutes, thereby to preparea green pixel sample for measurement. The thickness of the green pixelafter the preparation is adjusted to be 2.5 μm.

TABLE 13 Zinc Azo phthalocyanine nickel Clear Green pixel bromidepigment G36 G7 complex resist For Ex. I-1, 3, 5 21.3 0 0 20.1 58.6 and 7For Ex. I-2, 4, 6, 8 22.4 0 0 21.1 56.5 to 10 and Comp. Ex. I-3 and 4For Comp. Ex. I-1 0 0.0 13.0 14.4 72.6 For Comp. Ex. I-2 0 60.4 0 2.936.7

(5-3) Production Example I-15: Production of Blue Pixel (for ExamplesI-1 to 10 and Comparative Examples I-1 to 4)

A mill base is prepared in the same composition as in the P.R.254 casein Production Example I-13 except for a change of the pigment toP.G.15:6, and is subjected to a dispersion treatment under similardispersion conditions for a residence time of one hour, thereby toobtain a P.G.15:6 dispersed ink.

Further, a mill base is prepared in the same composition as in the P.R.case in Production Example I-13 except for a change of the pigment topigment violet (hereinafter referred to as “P.V.”) 23, and is subjectedto a dispersion treatment under similar dispersion conditions for aresidence time of two hours, thereby to obtain a P.V.23 dispersed ink.

Here, the P.G.36 dispersed ink is obtained in the same manner asdisclosed in the above Production Example I-14.

The dispersed inks obtainable as described above, and the resistsolution prepared in the above Production Example I-12 are mixed andstirred in the compounding ratio as shown in the following Table 14, anda solvent (propylene glycol monomethyl ether acetate) is added to bringthe final solid content concentration to be 25 wt %, thereby to obtain acomposition for a blue color filter.

The composition for a color filter thus obtained is applied on a glasssubstrate of 10 cm×10 cm (“AN100”, manufactured by Asahi Glass Company,Limited) by a spin coater and dried. The entire surface of thissubstrate is irradiated with ultraviolet light with an exposure amountof 100 mJ/cm², followed by development with an alkali developer and thenby post-baking in an oven at 230° C. for 30 minutes, thereby to preparea blue pixel sample for measurement. The thickness of the blue pixelafter the preparation is adjusted to be 2.5 μm.

TABLE 14 Blue pixel B15:6 V23 G36 Clear resist For Ex. I-1, 3, 5 and 78.0 2.7 0 89.3 For Ex. I-2, 4, 6, 8 14.4 4.9 0 80.7 to 10 and Comp. Ex.I-3 and 4 For Comp. Ex. I-1 7.7 2.7 0 89.6 For Comp. Ex. I-2 16.4 1.49.7 72.5

(5-4) Color Filters

Color filters of Examples I-1 to 10 and Comparative Examples I-1 to 4are prepared by combining the red, green and blue pixels shown in Tables12 to 14. With respect to the respective color filters for Examples I-1,3, 5 and 7, the transmittance spectrum of each of the red pixel sample,the green pixel sample and the blue pixel sample was calculated, and theresults are shown in FIG. 10. With respect to the respective colorfilters for Examples I-2, 4, 6, 8 to 10 and Comparative Examples I-3 and4, the transmittance spectrum of each of the red pixel sample, the greenpixel sample and the blue pixel sample was calculated, and the resultsare shown in FIG. 11.

(6) Color Image Display Devices (6-1) Examples I-1 to 10 and ComparativeExamples I-1 to 4

Color image display devices of Examples I-1 to 10 and ComparativeExamples I-1 to 4 were prepared by combining the backlights (BL-1 toBL-9) shown in Production Examples I-1 to 9 and color filters forExamples I-1 to 10 and Comparative Examples I-1 to 4. With respect tothese color image display devices, the chromaticity (x, y, Y) wasmeasured, and also the color reproducibility (NTSC ratio) and thebrightness (color temperature) were obtained. Here, the value Ycorresponds to the use efficiency of light emitted from the backlight.The results are shown in Tables 15(a) and 15(b).

TABLE 15(a) Phosphor BSON + KTF β-SiAlON + KTF BSON + BaTiF₆ B-SiAlON +BaTiF₆ Yellow phosphor Backlight BL-5 BL-1 BL-2 BL-3 BL-4 Comp. Comp.Color filter Ex. I-1 Ex. I-2 Ex. I-3 Ex. I-4 Ex. I-5 Ex. I-6 Ex. I-7 Ex.I-8 Ex. I-1 Ex. I-2 Red x 0.679 0.682 0.675 0.679 0.680 0.684 0.6760.680 0.645 0.660 y 0.320 0.317 0.324 0.321 0.318 0.316 0.323 0.3200.330 0.330 Y 25.4 24.3 22.9 21.7 26.1 24.9 23.3 22.1 16.00 14.30 Greenx 0.262 0.260 0.289 0.287 0.261 0.259 0.289 0.287 0.275 0.250 y 0.6580.661 0.658 0.661 0.658 0.661 0.658 0.661 0.600 0.650 Y 54.1 53.3 56.655.7 53.5 52.7 56.1 55.3 42.10 30.20 Blue x 0.150 0.144 0.152 0.1450.150 0.144 0.152 0.145 0.150 0.140 y 0.073 0.044 0.065 0.039 0.0720.044 0.064 0.039 0.060 0.080 Y 10.4 4.8 9.0 4.2 10.4 4.8 9.1 4.2 5.105.80 White x 0.318 0.333 0.317 0.330 0.321 0.336 0.318 0.332 0.311 0.310y 0.295 0.309 0.299 0.314 0.293 0.307 0.296 0.312 0.310 0.310 Y 30.027.4 29.5 27.2 30.0 27.5 29.5 27.2 21.1 16.8 Color temperature (K) 64545446 6522 5602 6269 5273 6458 5526 6781 6824 NTSC ratio (%) 89.0 95.086.7 92.2 89.5 95.5 87.2 92.6 74 85

TABLE 15(b) Blue emitting phosphor SCA SCA SCA SCA Green emittingphosphor GBAM GBAM GBAM GBAM Red emitting phosphor KSF CASN660 KSFCASN660 Backlight BL-6 BL-7 BL-8 BL-9 Color filter Ex. I-9 Comp. Ex. I-3Ex. I-10 Comp. Ex. I-4 Red x 0.70 0.687 0.694 0.688 y 0.30 0.312 0.3050.312 Y 30.2 29.7 25.0 27.3 Green x 0.170 0.210 0.162 0.204 y 0.7230.704 0.727 0.705 Y 51.2 52.3 54.9 53.2 Blue x 0.151 0.154 0.151 0.153 y0.042 0.038 0.039 0.036 Y 3.9 3.5 4.7 4.4 White x 0.361 0.363 0.3140.329 y 0.324 0.327 0.304 0.297 Y 28.5 28.5 28.2 28.3 Color temperature(K) 4236 4157 6649 5685 NTSC ratio (%) 115.6 107 117 109

The value Y of white color in Tables 15(a) and 15(b) represents thelight use efficiency of backlight as the entire color image displaydevice. As shown in Tables 15(a) and 15(b), when a color image displaydevice is designed to have a high color reproduction range with a NTSCratio of 85% exceeding the EBU standard (NTSC ratio: 72%), aconventional backlight brings about a remarkable decrease of the valueY, while by using the technique of the present invention, a high levelof the value Y can be accomplished. Namely, it becomes possible toobtain a higher luminance by a low power consumption.

Further, even a NTSC ratio exceeding Adobe-RGB (NTSC ratio: 94%) whichwas not accomplished by a conventional backlight, since the thickness ofthe color filter tended to be too thick (>10 μm), and the plate makingproperty was not obtained, can be accomplished by using the technique ofthe present invention. Each of the coating films made of thecompositions for the respective color filters prepared in the aboveProduction Examples I-9 to 11 was exposed with 100 mJ/cm² by using atest pattern mask, followed by development, whereby it was confirmedthat good patterns were obtained with respect to all samples. The filmthickness after drying of the composition for each color filter actuallyprepared was 2.50 μm in each case.

Group II of Examples M^(I)′₂M^(IV)′F₆:R and Process for Producing LightEmitting Device Employing it Methods for Measuring Physical PropertyValues

The physical property values of the phosphors obtained in the followingExamples and Comparative Examples were measured and calculated by thefollowing methods.

{Emission Characteristics} <Emission Spectrum>

The emission spectrum was measured at room temperature (25° C.) by usinga fluorometer (manufactured by JASCO Corporation) equipped with a 150 Wxenon lamp as an excitation light source and a multichannel CCD detectorC7041 (manufactured by Hamamatsu Photonics K.K.) as a spectrum-measuringapparatus.

More specifically, light from an excitation light source is passedthrough a diffraction grating spectroscope having a focal distance of 10cm, so that a phosphor is irradiated with only excitation light with awavelength of at most 455 nm via an optical fiber. Light generated fromthe phosphor under irradiation with the excitation light wasspectroscopically separated by a diffraction grating spectroscope havinga focal distance of 25 cm, and emission peak intensities of therespective wavelengths were measured by a spectrum-measuring apparatuswithin a wavelength range of from 300 nm to 800 nm, and an emissionspectrum was obtained via signal treatment such as sensitivitycorrection by a personal computer. During the measurement, the slidwidth of the light-receiving side spectroscope was set to be 1 nm forthe measurement.

<Luminance>

The relative luminance was calculated from the stimulus value Y in anXYZ color system calculated in accordance with JIS Z8724 within a rangehaving the excitation wavelength region removed from the emissionspectrum in the visible region obtained by the above-described method,as a relative value (hereinafter sometimes referred to simply as“luminance”) to 100% being the stimulus value Y obtained in the samemanner within a range having the excitation wavelength removed from theemission spectrum obtained by exciting yellow-emitting phosphorY₃Al₅O₁₂:Ce (product number: P46-Y3) manufactured by Kasei Optonix, Ltd.with excitation light with a wavelength of 455 nm in the same manner.

<Excitation Spectrum>

The excitation spectrum was measured at room temperature (25° C.) byusing Fluorescence spectrophotometer F-4500 manufactured by Hitachi,Ltd. More specifically, the red color emission peak at 631 nm wasmonitored to obtain an excitation spectrum within a wavelength range offrom 300 nm to 550 nm.

{Particle Size} <Weight-Average Median Diameter D₅₀ and Particle SizeDistribution>

The particle size distribution of a phosphor was measured by a laserdiffraction/scattering type particle size distribution-measuringapparatus LA-300 manufactured by HORIBA, Ltd. Here, prior to themeasurement, the phosphor was dispersed by using ethanol as a dispersionsolvent, then the initial transmittance on the optical axis was adjustedto be about 90%, and the measurement was carried out by suppressing theinfluence by aggregation to the minimum while stirring the dispersionsolvent by a magnet stirrer.

The weight-average median diameter D₅₀ was calculated as a particlediameter value when the integrated value of the particle sizedistribution (corresponding to the weight base particle sizedistribution curve) obtained as described above was 50%.

<Quantile Deviation (QD) of Particle Size Distribution>

The quantile deviation (QD) of the particle size distribution wascalculated by using the following formula, where D₂₅ and D₇₅ areweight-average median diameters when the integrated value of themeasured particle size distribution was 25% and 75%, respectively.

QD=|D ₇₅-D ₂₅ |/|D ₇₅ +D ₂₅

{Shape of Phosphor Particles} <Scanning Electron Microscopic (SEM)Photograph>

In order to observe the shape, etc. of the phosphor particles, a SEMphotograph was taken at 1.000-fold magnification (Examples II-1-2 andII-1-9) or 5.000-fold magnification (Example II-1-1, Comparative ExampleII-1-1) by using SEM (S-3400N, manufactured by Hitachi, Ltd.) in eachExample or Comparative Example.

<Specific Surface Area>

The measurement of the specific surface area was carried out by anitrogen adsorption BET 1 point method by means of a fully automaticspecific surface area-measuring apparatus (fluid process) AMS1000A,manufactured by Ohkura Riken Co., Ltd.

{Analysis of Chemical Composition} <Sem-Edx Method>

In the chemical composition analysis of the concentration of Mncontained in a phosphor, the measurement was carried out by a SEM-EDXmethod by using SEM (S-3400N, manufactured by Hitachi, Ltd.) as ameasuring apparatus and an energy dispersion X-ray analyzer (EDX)EX-250x-act manufactured by HORIBA, Ltd. Specifically, in the scanningelectron microscopic (SEM) measurement, a phosphor was irradiated withan electron beam at an accelerating voltage of 20 kV, and characteristicX-rays discharged from the respective elements contained in the phosphorwere detected to carry out the elemental analysis.

{Quantum Efficiency}

<Absorption Efficiency α_(q), Internal Quantum Efficiency η_(i) andExternal QUANTUM EFFICIENCY η_(o)>

In order to determine the quantum efficiency (absorption efficiencyα_(q), internal quantum efficiency η_(i) and external quantum efficiencyη_(o), firstly, a phosphor sample to be measured (e.g. a phosphor powderor the like) was treated to make the surface sufficiently smooth andpacked into a cell so that the measurement accuracy be maintained, andit was attached to a light-concentrating device such as an integratingsphere.

To the light-concentrating device, a Xe lamp was attached as an emissionlight source to excite the phosphor sample. Further, in order to bringthe emission peak wavelength of the emission light source to be a singlecolor light of 455 nm, adjustment was carried out by using a filter or amonochlometer (diffraction grating spectroscope).

The phosphor sample to be measured was irradiated with the light fromthe emission light source having the emission peak wavelength thusadjusted, whereby the spectrum including the emission (fluorescence) andreflected light was measured by a spectroscopic apparatus (MCPD7000,manufactured by Otsuka Electrics Co., Ltd.).

<Absorption Efficiency α_(q)>

The absorption efficiency α_(q) was calculated as a value obtained bydividing the photon number N_(abs) of the excitation light absorbed bythe phosphor sample, by the total photon number N of the excitationlight.

A specific calculation procedure is as follows.

Firstly, the latter total photon number N of the excitation light wasdetermined as follows.

That is, a substance having a reflectance R of substantially 100% to theexcitation light, e.g. a white reflector plate such as “Spectralon”(having a reflectance R of 98% to excitation light of 455 nm)manufactured by Labsphere, was attached, as an object to be measured, tothe above-mentioned light-concentrating device in the same dispositionas the phosphor sample, and the reflection spectrum was measured (thisreflection spectrum is hereinafter referred to as “I_(ref) (λ)”) bymeans of the spectrophotometer.

From this reflection spectrum I_(ref) (A), a numerical value representedby the following formula I was obtained. Here, the integral interval ofthe following formula I was set to be from 435 nm to 465 nm. Thenumerical value represented by the following formula I is proportionalto the total photon number N of the excitation light.

$\begin{matrix}{\frac{1}{R}{\int{{\lambda \cdot {I_{ref}(\lambda)}}{\lambda}}}} & {{{Formula}\mspace{14mu} I}\mspace{14mu}}\end{matrix}$

Further, from the reflection spectrum I(λ) when the phosphor sample asan object having an absorption efficiency α_(q) to be measured wasattached to the light-concentrating device, a numerical valuerepresented by the following formula II was determined. Here, theintegral interval of the formula II was set to be the same as theintegral interval set for the above formula I. The numerical valueobtained by the following formula II is proportional to the photonnumber N_(abs) of the excitation light absorbed by the phosphor sample.

$\begin{matrix}{{\frac{1}{R}{\int{{\lambda \cdot {I_{ref}(\lambda)}}{\lambda}}}} - {\int{{\lambda \cdot {I(\lambda)}}{\lambda}}}} & {{{Formula}\mspace{14mu} {II}}\mspace{14mu}}\end{matrix}$

From the foregoing, the absorption efficiency α_(q) was calculated bythe following formula.

absorption efficiency α_(q) =N _(abs) /N=Formula II/Formula I

<Internal Quantum Efficiency η_(i)>

The internal quantum efficiency η_(i), was calculated as the valueobtained by dividing the photon number N_(PL) derived from thefluorescence phenomenon, by the photon number N_(abs) of light absorbedby the phosphor sample.

From the above I(λ), a numerical value represented by the followingformula III was obtained. Here, the lower limit for the integralinterval of the formula III was set to be from 466 nm to 780 nm. Thenumerical value obtainable by the following formula III is proportionalto the photon number N_(PL) derived from the fluorescence phenomenon.

∫λ·I(λ)dλ  Formula III

From the foregoing, the internal quantum efficiency η_(i) was calculatedby the following formula.

η_(i)=Formula III/Formula II

<External quantum efficiency η_(o)>

The external quantum efficiency η_(o) was calculated as a product of theabsorption efficiency α_(q) and the internal quantum efficiency η_(i)obtained by the above procedure.

{Powder X-Ray Diffraction Measurement for Common Identification}

The powder X-ray diffraction was precisely measured by a powder X-raydiffraction apparatus X'Pert manufactured by PANalytical. Themeasurement conditions are as follows.

CuKα tube used

X-ray output=45 kV, 40 mA

Divergence slit=automatic, irradiation width: 10 mm×10 mm

Detector=semiconductor array detector X'Celerator used, Cu filter used

Scanning range 2θ=10 to 65°

Read width=0.0167°

Measuring time=10 sec.

Raw Materials Used

The raw materials used in the following Examples and ComparativeExamples are shown in the following Table 16.

TABLE 16 Chemical Purity Name of raw material formula (wt %)Manufacturer Notes Potassium K₂SiF₆ 99.9 Morita Chemicalhexafluorosilicate Industries Co., Ltd. Potassium K₂MnF₆ — — Prepared bythe method hexafluoromanganate disclosed in the (IV) followingPreparation Example II-1 Hydrofluoric acid HF 47.3 Kanto Chemical Co.,Inc. Potassium hydrogen KHF₂ 99 Wako Pure Chemical fluoride Industries,Ltd. Hexafluorosilicic acid H₂SiF₆ 33 Kanto Chemical Co., Inc. AcetoneCH₃COCH₃ 99.5 Junsei Chemical Co., Ltd. Ethanol C₂H₅OH 99.5 JunseiChemical Co., Ltd. Acetic acid CH₃COOH 99.9 Kanto Chemical Co., Inc.

Preparation of K₂MnF₆ Preparation Example II-1

K₂MnF₆ can be obtained by the following reaction formula.

That is, KF powder or KHF₂ powder was dissolved in hydrofluoric acid(47.3 wt %) and then KMnO₄ powder was put into this solution anddissolved. While stirring the solution, an aqueous hydrogen peroxidesolution was dropwise added, whereby a yellow precipitate was obtainedwhen the molar ratio of KMnO₄ to H₂O₂ became 1.5. The precipitate waswashed with acetone and dried at 130° C. for one hour to obtain K₂MnF₆.In the following Examples and Comparative Examples, K₂MnF₆ prepared asdescribed above, was used.

Examples and Comparative Examples for Preparation of Phosphor(K₂Mnf₆:Mn) Example II-1-1

So that the feedstock composition for a phosphor would be K₂ Si_(0.9)Mn_(0.1) F₆, as raw material compounds, K₂ SiF₆ (1.7783 g) and K₂ MnF₆(0.2217 g) were added and dissolved in 70 ml of hydrofluoric acid (47.3wt %) with stirring under atmospheric pressure at room temperature.After the respective raw material compounds were all dissolved, 70 ml ofacetone was added at a rate of 240 ml/hr while stirring the solution toprecipitate the solution in the poor solvent. The obtained phosphor waswashed with ethanol and dried at 130° C. for one hour to obtain 1.7 g ofa phosphor.

From the X-ray diffraction pattern of the obtained phosphor, it wasconfirmed that K₂SiF₆:Mn was prepared. The X-ray diffraction pattern ofthis K₂SiF₆:Mn is shown in FIG. 12.

Further, the excitation spectrum and the emission spectrum of theobtained phosphor are shown in FIG. 13. From the excitation spectrum, itis evident that the excitation is within a range of from 450 to 460 nm,and the excitation light from the blue emitting LED chip can efficientlybe absorbed. Further, the emission peak of the phosphor obtained in thisExample has the main emission peak wavelength at 631 nm and shows anarrow band red color with a half-value width of 6 nm, and it can besaid that it shows fluorescent characteristics suitable for the purposeof the present invention.

Example II-1-2

4.9367 g of KHF₂ and 0.8678 g of K₂ MnF₆ were weighed and dissolved in20 ml of hydrofluoric acid (47.3 wt %). With stirring at 26° C., thissolution was added to a solution mixture of 10 ml of a 33 wt % H₂ SiF₆aqueous solution and 10 ml of hydrofluoric acid (47.3 wt %) to letyellow crystals precipitate. The obtained crystals were subjected tofiltration with filter paper No. 5C, then washed four times with 100 mlof ethanol and dried at 130° C. for one hour to obtain 6.2 g of aphosphor.

From the X-ray diffraction pattern of the obtained phosphor, it wasconfirmed that K₂ MnF₆:Mn was prepared. The X-ray diffraction of this K₂MnF₆:Mn is shown in FIG. 12.

Example II-1-9

4.9367 g of KHF₂ was weighed and dissolved in 10 ml hydrofluoric acid(47.3 wt %).

On the other hand, 0.8678 g of K₂ MnF₆ was weighed, and it was added anddissolved in a solvent mixture of 10 ml of a 33 wt % H₂ SiF₆ aqueoussolution and 40 ml of hydrofluoric acid (47.3 wt %) to prepare asolution. While stirring this solution at 26° C., the above hydrofluoricacid having KHF₂ dissolved, was added to this solution to let yellowcrystals precipitate. The obtained crystals were subjected to filtrationwith filter paper No. 5C, then washed four times with 100 ml of ethanoland dried at 150° C. for two hour to obtain 5.9 g of a phosphor.

Comparative Example II-1-1

A phosphor was obtained in the same manner as in Example II-1-1 exceptthat acetone as the poor solvent was added all at once.

From the X-ray diffraction pattern of the obtained phosphor, it wasconfirmed that K₂SiF₆:Mn was prepared. The X-ray diffraction pattern ofthis K₂SiF₆:Mn is shown in FIG. 12.

Comparison of Phosphors Obtained in Examples II-1-1, II-1-2 and II-1-9and Comparative Example II-1-1

With respect to the phosphors obtained in Examples II-1-1, II-1-2 andII-1-9 and Comparative Example II-1-1, the Mn concentration (“analyzedMn concentration (mol %)” in Table 17, the same applies hereinafter)obtained as a result of the composition analysis by SEM-EDX and theluminance (relative value to 100 of P46Y3), absorption efficiency,internal quantum efficiency and external quantum efficiency, determinedfrom the emission spectrum obtained by excitation with light having awavelength of 455 nm, are shown in Table 17.

Further, the results of the specific surface area measurement and theweight-average median diameter D₅₀ and the quantile deviation (QD) ofthe particle size distribution, obtained by the measurement of theparticle size distribution are shown in Table 18.

Further, the particle size distribution curves are shown in FIGS. 14Aand 14B, and the SEM photographs are shown in FIGS. 15A and 15B,respectively.

TABLE 17 Internal External Charged Mn Analyzed Mn Absorption quantumquantum concentration concentration efficiency efficiency efficiency(mol %) (mol %) Luminance (%) (%) (%) Ex. II-1-1 10 2.5 24.4 39.6 91.836.4 Ex. II-1-2 10 3.1 26.7 — — — Ex. II-1-9 10 6.3 31 85 46.2 39.3Comp. 10 4.2 20.4 40.2 71.5 28.7 Ex. II-1-1

TABLE 18 Median diameter Quantile deviation Specific surface (D₅₀) in(QD) of particle area (m²/g) Examples (μm) size distribution Ex. II-1-10.91 18.9 0.374 Ex. II-1-2 0.37 26.8 0.323 Ex. II-1-9 0.43 27.4 0.263Comp. 1.56 8.8 0.843 Ex. II-1-1

From the above results, the following is evident.

In Example II-1-1, as a result of slowing down the precipitation rate byaddition of a poor solvent as compared with Comparative Example II-1-1,the luminance became high despite the concentration of Mn as anactivated element (analyzed Mn concentration in Table 17) became low.The reason is considered to be such that by controlling theprecipitation rate, activation of Mn ions was uniformly carried out,whereby the internal quantum efficiency became high.

In addition, from the particle size distribution curves in FIGS. 14A and14B, the phosphor in Comparative Example II-1-1 has a doubledistribution, and it is considered that small particles are aggregated,while the phosphor in Example II-1-1 has many particles larger than thephosphor in Comparative Example II-1-1 and has little small particles,and thus it is evident that there is no aggregation or no doubledistribution, and there is only one peak. This is evident also from theresults of measurement of the specific surface area and theweight-average median diameter D₅₀.

It is considered that the particles having a small specific surface areaas obtained in Example II-1-1 have improved durability, since theircontact area with exterior becomes small.

On the other hand, the phosphors obtained by the methods of ExamplesII-1-2 and II-1-9 are free from a double distribution in their particlesize and free from small particles, as evident from their SEMphotographs, particle size distribution curves, specific surface areasand weight-average median diameters D₅₀, and thus they are obtained inthe form of large particles free from aggregation. It is considered thatthe absorption efficiency thereby became substantially high, as aresult, the luminance also became high.

Further, with the phosphors obtained in Examples II-1-2 and II-1-9, fromtheir shapes, angular hexagonal particles are substantially observed(FIG. 15A). Their specific surface areas are also substantially small ascompared with the phosphors in Example II-1-1 and Comparative ExampleII-1-1, and it is considered that the durability is also improved as thecontact area with exterior become small.

Examples II-1-3 to II-1-6

Phosphors were obtained in the same manner as in Example II-1-1 exceptthat the concentration of charged Mn was changed as identified in Table19. With respect to the obtained phosphors, the analyzed Mnconcentrations, the luminance (relative value to 100 of P46Y3) obtainedfrom the emission spectra obtained by excitation with light having awavelength of 455 nm, the absorption efficiencies, the internal quantumefficiencies and the external quantum efficiencies, as well as thequantile deviations (QD) in their particle size distributions, are shownin Table 19 together with the results of Example II-1-1.

Examples II-1-7, II-1-8, II-1-10 to II-1-15

Phosphors were obtained in the same manner as in Example II-1-2 exceptthat the concentration of charged Mn was changed as identified in Table19.

With respect to the obtained phosphors, the analyzed Mn concentrations,the luminance (relative value to 100 of P46Y3) obtained from theemission spectra obtained by excitation with light having a wavelengthof 455 nm, the absorption efficiencies, the internal quantumefficiencies and the external quantum efficiencies, as well as thequantile deviations (QD) in their particle size distributions, are shownin Table 19 together with the results of Example II-1-2 and II-1-9.

TABLE 19 Internal External Quantile Charged Mn Analyzed Mn Absorptionquantum quantum deviation (QD) of concentration concentration efficiencyefficiency efficiency particle size (mol %) (mol %) Luminance (%) (%)(%) distribution Ex. II-1-3 3 1.1 16.3 26 95 25 — Ex. II-1-4 5 1.1 20.831 100 31 — Ex. II-1-1 10 2.5 24.4 40 92 36 0.374 Ex. II-1-5 15 3.3 27.746 87 40 — Ex. II-1-6 20 5.2 23.7 57 55 31 — Ex. II-1-7 5 3.0 23.5 — — —— Ex. II-1-2 10 3.1 26.7 — — — 0.323 Ex. II-1-8 15 4.8 23.9 — — — — Ex.II-1-10 1 0.4 23 45.5 73.0 33.2 0.331 Ex. II-1-11 3 2.0 32 65.8 68.745.2 0.292 Ex. II-1-12 5 3.8 34 75.1 59.5 44.6 0.301 Ex. II-1-13 7.5 4.533 83.5 50.2 41.9 0.278 Ex. II-1-9 10 6.3 31 85.0 46.2 39.3 0.263 Ex.II-1-14 15 11.4 30 83.6 43.7 36.5 0.223 Ex. II-1-15 20 19.6 28 88.8 38.734.4 0.217

From Table 19, it is evident that in the preparation by (1) a poorsolvent separation method as represented by Examples II-1-1, -3, -4, -5and -6, it is preferred that the charged Mn concentration is at least 10mol % and at most 15 mol %, and the concentration in crystals i.e. theanalyzed Mn concentration is at least 2 mol % and at most 4 mol %. It isalso evident that in the preparation by (2-1) a method of mixing asolution containing at least Si and F with a solution containing atleast K, Mn and F as represented by Examples II-1-2, -7 and -8, it ispreferred that the charged Mn concentration is at least 5 mol % and atmost 15 mol %, and the concentration in crystals i.e. the analyzed Mnconcentration is at least 3 mol % and at most 5 mol %. Further, it isevident that in the preparation by (2-2) a method of mixing a solutioncontaining at least Si, Mn and F with a solution containing at least KFas represented by Examples II-1-9, -11, -12, -13, -14 and -15, it ispreferred that the charged Mn concentration is at least 3 mol % and atmost 10 mol %, and the concentration in crystals i.e. the analyzed Mnconcentration is at least 2 mol % and at most 6 mol %.

Comparative Examples II-1-2 and II-1-3

A phosphor was obtained in the same manner as in Comparative ExampleII-1-1 except that instead of acetone as a poor solvent, ethanol(Comparative Example II-1-2) or acetic acid (Comparative Example II-1-3)was used.

The quantile deviation (QD) of the particle size distribution obtainedwith respect to the obtained phosphor is shown in Table 20 together withthe results in Comparative Example II-1-1.

TABLE 20 Quantile deviation (QD) of the particle Poor solvent sizedistribution Comparative Example II-1-1 Acetone 0.843 ComparativeExample II-1-2 Ethanol 0.773 Comparative Example II-1-3 Acetic acid0.688

Examples and Comparative Examples for Semiconductor Light EmittingDevice Example II-2-1

Using a 350 μm square chip GU35R460T manufactured by Showa Denko K.K. asa blue emitting diode (hereinafter sometimes referred to as “LED”) whichemits light with a dominant emission wavelength of from 455 nm to 465 nm(the emission peak wavelength of from 451 nm to 455 nm) and with ahalf-value width of the emission peak of 22 to 28 nm, it was bonded tothe terminals at the bottom of a concave portion of a 3528SMD type PPAresin package by a silicone resin base transparent die bond paste. Then,it was heated at 150° C. for two hours to cure the transparent die bondpaste, and then the blue emitting LED and the electrodes of the packagewere wire-bonded by a gold metal having a diameter of 25 μm.

On the other hand, 0.051 g of a green emitting phosphor Ba_(1.36)Sr_(0.49)EU_(0.15) SiO₄ (identified by “BSS” in Table 21) having anemission peak wavelength of 528 nm and an emission peak half-value widthof 68 nm prepared in the after-mentioned Preparation Example II-2 forphosphor, 0.189 g of a red emitting phosphor (identified by “KSF” inTable 21) having an emission peak wavelength of 631 nm and an emissionpeak half-value width of 6 nm, prepared in Example II-1-1, 0.880 g of asilicone resin (JCR6101up) manufactured by Dow Corning Toray SiliconeCo., Ltd. and 0.026 g of AEROSIL (RX200) manufactured by Nippon AerosilCo., Ltd., were weighed and mixed by an agitation defoaming apparatusAR-100 manufactured by Thinky Corporation to obtain aphosphor-containing composition.

Then, 4 μl of the phosphor-containing composition thus obtained wasinjected into a concave portion of the above-mentioned SMD type resinpackage having the blue emitting LED mounted. Then, heating was carriedout at 70° C. for one hour and then at 150° C. for 5 hours to cure thephosphor-containing composition thereby to obtain a semiconductor lightemitting device.

A current of 20 mA was conducted to the blue emitting LED chip of thewhite color semiconductor light emitting device thus obtained to let itemit light. The CIE chromaticity coordinate values of the emission weremeasured, whereby x/y=0.319/0.327. The obtained emission spectrum isshown in FIG. 16. The white luminous flux from the semiconductor lightemitting device to the light output from the blue emitting LED was 236lumen/VV.

Further, in a case where this semiconductor light emitting device isused as a liquid crystal backlight, with respect to a color imagedisplay device obtained by a combination of this with the optimizedcolor filter obtained in Production Example II-1 given hereinafter, thechromaticity (x, y, Y) was found to be (0.321, 0.341, 27.3), and withrespect to the color reproducibility (NTSC ratio) and the color tone(color temperature), they were found to be an NTSC ratio of 95 and acolor temperature of 5999K. Here, value Y in the chromaticity (x, y, Y)corresponds to the use efficiency of the emission from the backlight.

Despite the same emission use efficiency, it was possible to obtain ahigher NTSC ratio by using the semiconductor light emitting device inthis Example obtained by using the red emitting phosphor of the presentinvention obtained in Example II-1-1 than the semiconductor lightemitting device in the after-mentioned Comparative Example II-2-1obtained by using known CaAlSiN₃:Eu.

Comparative Example II-2-1

A semiconductor light emitting device in Comparative Example II-2-1 wasobtained by the same operation as in Example II-2-1 except that in thepreparation of the semiconductor light emitting device in ExampleII-2-1, 0.060 g of a green emitting phosphor Ba_(1.36) Sr_(0.49)EU_(0.15) SiO₄ (identified by “BSS” in Table 21), 0.010 g of a redemitting phosphor “BR-101A” (CaAlSiN₃:Eu, identified by “CASN” in Table21) having an emission peak wavelength of 650 nm and an emission peakhalf-value width of 92 nm, manufactured by Mitsubishi ChemicalCorporation, 0.618 g of a silicone resin (SCR1011) manufactured byShin-Etsu Chemical Co., Ltd and 0.019 g of AEROSIL (RX200) manufacturedby Nippon Aerosil Co., Ltd., were weighed.

A current of 20 mA was conducted to the blue emitting LED chip of thewhite color semiconductor light emitting device thus obtained to let itemit light. The CIE chromaticity coordinate values of the emission weremeasured, whereby x/y=0.312/0.319. The obtained emission spectrum isshown in FIG. 17. The white luminous flux from the semiconductor lightemitting device to the light output from the blue emitting LED was 234lumen/W.

Further, in a case where this semiconductor light emitting device isused as a liquid crystal backlight, with respect to a color imagedisplay device obtained by a combination of this with the optimizedcolor filter obtained in Production Example II-1 given hereinafter, thechromaticity (x, y, Y) was found to be (0.330, 0.331, 27.3), and withrespect to the color reproducibility (NTSC ratio) and the color tone(color temperature), they were found to be an NTSC ratio of 87 and acolor temperature of 5611K.

Example II-2-2

Using a 290 μm square chip C395 MB290 manufactured by Cree as a nearultraviolet emitting diode having a dominant emission wavelength of from390 nm to 400 nm, it was bonded to the terminals at the bottom of aconcave portion of a 3528SMD type PPA resin package by a silicone resinbase transparent die bond paste. Then, it was heated at 150° C. for twohours to cure the transparent die bond paste, and then the nearultraviolet emitting LED and the electrodes of the package werewire-bonded by a gold metal having a diameter of 25 μm.

On the other hand, 0.038 g of Sr₁₀(PO₄)₆Cl₂:Eu (identified by “SCA” inTable 21) having an emission peak wavelength of 450 nm and an emissionpeak half-value width of 29 nm prepared in the above Preparation ExampleI-7 for phosphor, 0.083 g of BaMgAl₁₀O₁₇:Eu,Mn (identified by “GBAM” inTable II-5) having an emission peak wavelength of 517 nm and an emissionpeak half-value width of 27 nm, prepared in the above PreparationExample I-6 for phosphor, 0.407 g of a red emitting phosphor (identifiedby “KSF” in Table 21) prepared in the above Example II-1-1 for phosphorand 0.634 g of a silicone resin (JCR6101up) manufactured by Dow CorningToray Silicone Co., Ltd., were weighed and mixed by an agitationdefoaming apparatus AR-100 manufactured by Thinky Corporation to obtaina phosphor-containing composition.

Then, 4 μl of the phosphor-containing composition thus obtained wasinjected into the concave portion of the above-mentioned SMD type resinpackage having the near ultraviolet emitting LED mounted. Then, heatingwas carried out at 70° C. for one hour and then at 150° C. for 5 hoursto cure the phosphor-containing composition thereby to obtain a desiredsemiconductor light emitting device.

A current of 20 mA was conducted to the near ultraviolet emitting LED ofthe white color semiconductor light emitting device thus obtained todrive and let it emit light. The CIE chromaticity coordinate values ofthe emission were measured, whereby x/y=0.339/0.339. The obtainedemission spectrum is shown in FIG. 18. The white luminous flux from thesemiconductor light emitting device to the light output from the nearultraviolet emitting LED was 230 lumen/W.

By the semiconductor light emitting device in this Example obtained byusing the red emitting phosphor of the present invention obtained inExample II-1-1, it was possible to obtain a luminous flux per unitincident light energy remarkably higher than the semiconductor lightemitting device in the after-mentioned Comparative Example II-2-2obtained by using CaAlSiN₃:Eu having good color purity with an emissionpeak wavelength of 660 nm, although it was the semiconductor lightemitting device having substantially the same chromaticity coordinatevalues.

Further, in a case where this semiconductor light emitting device isused as a liquid crystal backlight, with respect to a color imagedisplay device obtained by a combination of this with the optimizedcolor filter obtained in Production Example 1 given hereinafter, thechromaticity (x, y, Y) was found to be (0.346, 0.374, 28.3), and withrespect to the color reproducibility (NTSC ratio) and the color tone(color temperature), they were found to be an NTSC ratio of 116 and acolor temperature of 5021K, respectively.

Despite substantially the same emission use efficiency, it was possibleto obtain a distinctly higher NTSC ratio by using the semiconductorlight emitting device in this Example obtained by using the red emittingphosphor obtained in Example II-1-1 than the semiconductor lightemitting device in the after-mentioned Comparative Example II-2 obtainedby using known CaAlSiN₃:Eu having good color purity and having anemission peak wavelength of 660 nm and an emission peak half-value widthof 95 nm.

Example II-2-3 and Comparative Examples II-2-2 and II-2-3

Semiconductor light emitting devices of Example II-2-3 and ComparativeExample II-2-2 and II-2-3 were obtained by the same operation as inExample II-2-2 except that in the preparation of the semiconductor lightemitting device in Example II-2-2, the type and amount of the phosphorused and the amount of the silicone resin were changed as shown in Table21. Here, in Example II-2-3 and Comparative Example II-2-3, as a blueemitting phosphor, Ba_(0.7) Eu_(0.3) MgAl₁₀ O₁₇ (identified by “BAM” inTable 21) having an emission peak wavelength of 455 nm and an emissionpeak half-value width of 51 nm, prepared in the after-mentionedPreparation Example II-3 for phosphor, was used. Further, as the redemitting phosphor in Comparative Example II-2-2 and Comparative ExampleII-2-3, a red emitting phosphor “BR-101B” (CaAlSiN₃:Eu, identified by“CASN660” in Table 21) manufactured by Mitsubishi Chemical Corporation,having an emission peak wavelength of 660 nm, was used.

A current of 20 mA was conducted to the ultraviolet emitting LED of thesemiconductor light emitting device thus obtained to drive and let itemit light. The CIE chromaticity coordinate values of the emission weremeasured and found to have the numerical values as identified in Table22. Further, the emission spectra of the semiconductor light emittingdevices obtained in Example II-2-3, Comparative Example II-2-2 andComparative Example II-2-3 are shown in FIGS. 19, 20 and 21,respectively.

Further, in a case where such a semiconductor light emitting device isused as a liquid crystal backlight, with respect to a color imagedisplay device obtained by a combination of this with the optimizedcolor filter obtained in Preparation Example II-1 given hereinafter, thechromaticity (x, y, Y), the color reproducibility (NTSC ratio) and thecolor tone (color temperature), were calculated and shown in Table 22.

TABLE 21 Types of phosphors Blend amounts (g) Blue Green Red Blue GreenRed emitting emitting emitting Silicone emitting emitting emitting Typeof LED phosphor phosphor phosphor resin AEROSIL phosphor phosphorphosphor Example II-2-1 Blue — BSS KSF 0.880 0.026 — 0.051 0.189Comparative emitting — BSS CASN 0.618 0.019 — 0.060 0.010 Example II-2-1LED Example II-2-2 Near SCA GBAM KSF 0.634 — 0.038 0.083 0.407Comparative ultraviolet SCA GBAM CASN660 0.610 — 0.025 0.082 0.008Example II-2-2 emitting Example II-2-3 LED BAM GBAM KSF 1.083 — 0.1350.096 0.331 Comparative BAM GBAM CASN660 1.274 — 0.124 0.119 0.013Example II-2-3

TABLE 22 Emission characteristics of semiconductor Emissioncharacteristics of color image display device light emitting device NTSCratio Color x y Lumen/W x y Y (%) (%) temperature (K) Example II-2-10.319 0.327 236 0.321 0.341 27.3 95 5999 Comparative 0.312 0.319 2340.330 0.331 27.3 87 5611 Example II-2-1 Example II-2-2 0.339 0.339 2300.346 0.374 28.3 116 5021 Comparative 0.329 0.318 174 0.371 0.364 28.4108 4168 Example II-2-2 Example II-2-3 0.277 0.315 227 0.311 0.347 27.9110 6493 Comparative 0.315 0.316 176 0.351 0.348 28.2 104 4744 ExampleII-2-3

Methods for Preparation of Phosphors

The phosphors used in the above Examples II-2-1 to II-2-3 andComparative Examples II-2-1 to II-2-3 were prepared as follows.

Preparation Example II-2

As phosphor raw materials, powders of barium carbonate (BaCO₃),strontium carbonate (SrCO₃), europium oxide (Eu₂ O₃) and silicon dioxide(SiO₂) were used. Each of these phosphor raw materials had a purity ofat least 99.9%, a weight average median diameter D₅₀ of at least 0.01 μmand at most 5 μm.

These phosphor raw materials were weighed so that the composition of aphosphor to be obtained would be Ba_(1.36) Sr_(0.49) Eu_(0.15) SiO₄.

Such phosphor raw material powders were mixed by an automatic mortaruntil the mixture became sufficiently uniform, and the mixture wasfilled in an alumina crucible and fired at 1,000° C. for 12 hours underatmospheric pressure in a nitrogen atmosphere.

Then, the content of the crucible was taken out, and as flux, 0.1 mol ofSrCl₂ and 0.1 mol of CsCl were added per mol of the phosphor, followedby mixing and pulverization by a dry system ball mill.

The obtained mixed pulverized product was again filled in an aluminacrucible, and solid carbon (in block form) was placed thereon, and analumina cover was placed. In a vacuum furnace, pressure was reduced to 2Pa by a vacuum pump, and then a hydrogen-containing nitrogen gas(nitrogen:hydrogen=96:4 (volume ratio)) was introduced to atmosphericpressure. This operation was repeated again, and then heating wascarried out at 1,200° C. for 4 hours under atmospheric pressure whilecirculating the hydrogen-containing nitrogen gas (nitrogen:hydrogen=96:4(volume ratio)) to carry out firing.

The obtained fired product was pulverized by a ball mill, followed bysieving in the form of slurry to remove coarse particles, followed bywashing with water and levigation to remove fine particles and then bydrying and sieving to disintegrate aggregated particles thereby toobtain a phosphor (BSS).

The obtained green emitting phosphor (BSS) had an emission peakwavelength of 528 nm and an emission peak half-value width of 68 nm.

Preparation Example II-3

As phosphor raw materials, 0.7 mol of barium carbonate (BaCO₃), 0.15 molof europium oxide (Eu₂O₃), 1 mol as Mg of basic magnesium carbonate(mass per mol of Mg: 93.17) and 5 mols of α-alumina (Al₂O₃) were weighedso that the chemical composition of a phosphor would be Ba_(0.7)EU_(0.3) MgAl₁₀ O₁₇ and mixed in a mortar for 30 minutes, then filled inan alumina crucible and fired at 1,200° C. for 5 hours in a box typefurnace while circulating nitrogen, and after cooling, the fired productwas taken out from the crucible and pulverized to obtain a precursor ofa phosphor.

To this precursor, 0.3 wt % of AlF₃ was added, followed by pulverizationand mixing for 30 minutes in a mortar. The mixture was filled in analumina crucible and fired at 1,450° C. for 3 hours in a box typefurnace in a nitrogen gas containing 4 wt % of hydrogen, and aftercooling, the obtained fired product was pulverized to obtain a pale bluepowder.

To this powder, 0.42 wt % of AlF₃ was added, followed by pulverizationand mixing for 30 minutes in a mortar. The mixture was filled in analumina crucible, and graphite in the form of beads was placed in aspace around the crucible, followed by firing at 1,550° C. for 5 hoursin a box type furnace by circulating nitrogen at a rate of 4 liter/min,and the obtained fired product was pulverized for 6 hours in a ballmill, classified by levigation and subjected to washing treatment withwater to obtain a blue emitting phosphor (BAM).

The obtained blue emitting phosphor (BAM) had an emission peakwavelength of 455 nm and an emission peak half-value width of 51 nm.

<Temperature Dependency of Phosphors>

Among phosphors used in the above Examples II-2-1 to II-2-3 andComparative Examples II-2-1 to II-2-3, with respect to KSF, CASN andBSS, the temperature dependency of the emission peak intensity wasmeasured, and the results are shown in the following Table 23.

TABLE 23 Emission Wavelength Variation rate Red peak range of ofemission emitting wavelength Half-value excitation peak intensityphosphor Type (nm) width (nm) band (nm) (%) Notes Ex. II-1-1 KSF 630 6310-510 15 455 nm excitation CASN 650 92 300-620 8 455 nm excitationEmission Wavelength Variation rate Green peak range of of emissionemitting wavelength Half-value emission peak intensity phosphor Type(nm) width (nm) (nm) (%) Notes Prep. Ex. II-2 BSS 526 66 475-615 11 455nm excitation

With respect to BAM as the blue emitting phosphor prepared in the abovePreparation Example II-3, the temperature characteristics underexcitation with a wavelength of 400 nm were measured, whereby thevariation rate of the emission peak intensity was 6%.

Method for Preparation of Optimized Color Filter

As the optimized color filter used in the above Examples II-2-1 toII-2-3 and Comparative Examples II-2-1 to II-2-3, the same one as “forExamples I-2, 4, 6, 8 to 10 and Comparative Examples I-3 and 4”disclosed in the above Production Example I-9 to 11, was used.

Group III of Examples Study on Improvement of Durability

Using the following semiconductor light emitting device, phosphor andphosphor-containing layer-forming liquid, a semiconductor light emittingdevice in each of the following Examples and Comparative Examples wasprepared, and evaluation of its durability was carried out by a lightingtest.

Semiconductor Light Emitting Device> Production Example III-1-1 VerticalSemiconductor Light Emitting Device

As a semiconductor light emitting device (A), a 290 μm square chip“C460EZ290” manufactured by CREE was bonded to terminals at the bottomof a concave portion of a 3528SMD type PPA resin package by a siliconeresin base transparent die bond paste. At that time, one bonding wirewas used.

Production Example III-1-2 Horizontal Semiconductor Light EmittingDevice

As a semiconductor light emitting device (A), a 350 μm square chip“GU35R460T” manufactured by Showa Denko K.K. was bonded to terminals atthe bottom of a concave portion of a 3528SMD type PPA resin package by asilicone resin base transparent die bond paste. At that time, twobonding wires were used.

Phosphors Preparation Example III-1 Red emitting phosphor K₂TiF₆:Mn⁴⁺

As raw material compounds, 4.743 g of K₂ TiF₆ and 0.2596 g of K₂ MnF₆were used so that the feedstock composition for phosphor would be K₂Ti_(0.95) Mn_(0.05) F₆. These raw material compounds were added, stirredand dissolved in 40 ml of hydrofluoric acid (concentration: 47.3 wt %)under atmospheric pressure at room temperature. After confirming thatthe respective raw material compounds were all dissolved, 60 ml ofacetone was added at a rate of 240 ml/hr while stirring the solution tolet a phosphor precipitate in the poor solvent. The obtained phosphorwas washed with acetone and dried at 100° C. for one hour.

From the X-ray diffraction pattern of the obtained phosphor, it wasconfirmed that K₂ Ti_(1-x) Mn_(x) F₆ was prepared. Further, the obtainedred emitting phosphor had a main emission peak with a peak wavelength of631 and a main emission peak half-value width of 7 nm, and the internalquantum efficiency was 65% as measured by the same method as describedin the description in GROUP II of Examples.

Further, the thermally decomposed fluorine amount and the variation rateof the emission peak intensity of this phosphor were measured by thefollowing method, and the results are shown in Table 24.

<Method for Measurement of Thermally Decomposed Fluorine Amount>

One gram of the phosphor was accurately weighed, then put in a platinumboat and set in an alumina core tube of a horizontal electric furnace.Then, the temperature in the furnace was raised while circulating argongas at a flow rate of 400 ml/min, and when the temperature of thephosphor became 200° C., it was maintained for two hours.

Here, the entire amount of argon gas circulated in the furnace wasabsorbed in a KOH aqueous solution (concentration: 67 mM), and theabsorbed liquid was analyzed by liquid chromatography to determine thethermally decomposed fluorine amount per minute per gram of thephosphor.

Preparation Example III-2 Red Emitting Phosphor K₂SiF₆:Mn⁴⁺

As raw material compounds, 1.7783 g of K₂ SiF₆ and 0.2217 g of K₂ MnF₆were used so that the feedstock composition for phosphor would be K₂Si_(0.9) Mn_(0.1) F₆. These raw material compounds were added, stirredand dissolved in 70 ml of hydrofluoric acid (47.3 wt %) underatmospheric pressure at room temperature. After confirming that therespective raw material compounds were all dissolved, 70 ml of acetonewas added at a rate of 240 ml/hr while stirring the solution to let aphosphor precipitate in the poor solvent.

The obtained phosphor was washed with ethanol and dried at 130° C. forone hour to obtain 1.7 g of the phosphor. From the X-ray diffractionpattern of the obtained phosphor, it was confirmed that K₂SiF₆:Mn wasprepared. Further, the obtained red emitting phosphor had a mainemission peak with a peak wavelength of 630 and a half-value width of 7nm, and the internal quantum efficiency was 94% as measured by the samemethod as described in the description in GROUP II of Examples.

Further, the thermally decomposed fluorine amount of this phosphor isshown in Table 24.

TABLE 24 THERMALLY DECOMPOSED FLUORINE AMOUNTS OF PHOSPHORS OBTAINED INPREPARATION EXAMPLES III-1 AND 2 Thermally decomposed Compositionfluorine amount (μg/min) Prep. Ex. 1 K₂Ti_(0.95)Mn_(0.05)F₆ 1.47 Prep.Ex. 2 K₂Si_(0.9)Mn_(0.1)F₆ 0.07 Reference Ex. CaF₂ (reagent chemical)0.004

Production Example III-2 Production of Fluoride ComplexPhosphor-Containing Layer (Material Layer B)-Forming Liquid

100 Parts by weight of a silicone resin SCR1016 manufactured byShin-Etsu Chemical Co., Ltd. and 12 parts by weight of the phosphorprepared in the above Preparation Example III-1 or III-2 were mixed byan agitation defoaming apparatus AR-100 manufactured by ThinkyCorporation to obtain a phosphor-containing layer-forming liquid (1) or(2).

Example III-1 Preparation of Semiconductor Light Emitting Device

Using a manually operated pipette, 4 μl of the phosphor-containinglayer-forming liquid (1) obtained in the above Production Example III-2was taken and injected to a semiconductor light emitting device havinginstalled the vertical type semiconductor light emitting device asdescribed in the above Production Example III-1-1. This semiconductorlight emitting device was maintained in a desiccator box which can beevacuated, for 5 minutes under conditions of 25° C. and 1 kPa, therebyto remove air bubbles included during the injection or dissolved air ormoisture. Thereafter, this semiconductor light emitting device wasmaintained at 70° C. for one hour and then at 150° C. for 5 hours tocure the forming liquid thereby to obtain a semiconductor light emittingdevice. With respect to the obtained semiconductor light emittingdevice, a lightning test was carried out by the method describedhereinafter, to evaluate the durability.

Comparative Example III-1

A semiconductor light emitting device was obtained and evaluation of thedurability was carried out in the same manner as in Example III-1 exceptthat the semiconductor light emitting device was changed to thehorizontal semiconductor light emitting device as disclosed in the aboveProduction Example III-1-2.

Example III-2

A semiconductor light emitting device was obtained, and evaluation ofthe durability was carried out in the same manner as in Example III-1except that instead of the phosphor-containing layer-forming liquid (1),the phosphor-containing layer-forming liquid (2) was used.

Comparative Example III-2

A semiconductor light emitting device was obtained and evaluation of thedurability was carried out in the same manner as in Example III-2 exceptthat the semiconductor light emitting device was changed to thehorizontal semiconductor light emitting device as disclosed in the aboveProduction Example III-1-2.

<Lighting Test>

A current of 20 mA was conducted to a semiconductor device, andimmediately after initiation of lighting (this point of time will bereferred to as “0 hour”), the emission spectrum was measured by using afiber multichannel spectrometer (USB2000 (integration wavelength range:200 nm to 1,100 nm, light receiving system: integrating sphere(diameter: 1.5 inch) manufactured by Ocean Optics, Inc).

Then, using an aging apparatus, LED AGING SYSTEM 100 ch LEDenvironmental test apparatus (YEL-51005 manufactured by YamakatsuElectronics Industry Co., Ltd.), a driving current of 20 mA wascontinuously conducted to the semiconductor light emitting device underconditions of 85° C. and a relative humidity of 85%, and upon expirationof each of 50 hours, 100 hours, 150 hours and 200 hours, from theinitiation of the current conduction, the emission spectrum was measuredin the same manner as at the time of the above 0 hour. Simultaneously,the semiconductor light emitting device was stored without conductingany current under conditions of 85° C. and a relative humidity of 85%,and upon expiration of each of 50 hours, 100 hours, 150 hours and 200hours, the emission spectrum was measured in the same manner as at thetime of above 0 hour by conducting the current only at the time of themeasurement.

The values of various emission characteristics (the entire luminousflux, luminance and chromaticity coordinates Cx, Cy) calculated from theemission spectrum obtained upon expiration of 200 hours are shown inTable 25, as relative values based on the measured value at 0 hour being100%.

In the lighting test, the emission spectrum was measured by maintainingthe spectrometer in a constant temperature tank of 25° C. to preventdata disturbance by a temperature change of the spectrometer itself.

TABLE 25 RESULTS OF DURABILITY TESTS OF SEMICONDUCTOR LIGHT EMITTINGDEVICES OBTAINED IN EXAMPLES III-1 AND 2 AND COMPARATIVE EXAMPLES III-1AND 2. Durability test results upon expiration of 200 hours Ex. III-1Comp. Ex. III-1 Ex. III-2 Comp. Ex. III-2 Not- Not- Not- Not- Lightedlighted Lighted lighted Lighted lighted Lighted lighted Measured Entireluminous 89%  80% 84% 76% 100% 100% 96% 94% items flux (μW) Luminance(lm) 94%  78% 92% 74% 100% 100% 98% 97% Cy 94% 101% 89% 94% 105% 100%95% 99% Cx 97% 100% 94% 97% 100% 100% 99% 101% 

In Examples III-1 and III-2 wherein the vertical type semiconductorlight emitting device was used, the decreases in the entire luminousflux and the luminance were small, and the color shift was little ascompared with Comparative Examples III-1 and III-2 wherein thehorizontal semiconductor light emitting device was used.

Further, from the comparison between Example III-1 and Example III-2, itwas found that K₂ Si_(0.9) Mn_(0.1) F₆ is superior in durability to K₂Ti_(0.95) Mn_(0.05) F₆ as a phosphor. The reason is considered to besuch that K₂ Si_(0.9) Mn_(0.1) F₆ has a lower solubility in water andits thermally decomposed fluorine amount is less.

Examples III-3 Preparation of Semiconductor Light Emitting Device

100 parts by weight of a two-pack type silicone resin SCR1016Amanufactured by Shin-Etsu Chemical Co., Ltd. and 100 parts by weight ofa curing agent SCR1016B were mixed and defoamed by an agitationdefoaming apparatus AR-100 manufactured by Thinky Corporation. 2 μL ofthe obtained liquid mixture was injected to a light emitting devicehaving the above-mentioned light emitting device installed andmaintained in a desiccator box which can be evacuated, for 5 minutesunder conditions of 25° C. and 1 kPa, thereby to remove air bubblesincluded during the injection or dissolved air or moisture. Thereafter,this semiconductor light emitting device was maintained underatmospheric pressure at 25° C. under a humidity of 50% to cure the abovesilicone resin layer thereby to form a material layer C.

Then, using a manually operated pipette, 2 μL of the above-mentionedfluoride complex phosphor-containing layer-forming liquid (1) wasinjected to the light emitting device and maintained at 100° C. for onehour and then at 150° C. for 5 hours to cure the material layer Bthereby to obtain a semiconductor light emitting device.

Examples III-4 Preparation of Semiconductor Light Emitting Device

Using a manually operated pipette, 2 μL of the above-mentioned fluoridecomplex phosphor-containing layer-forming liquid (1) was injected to thesemiconductor light emitting device and maintained at 100° C. for onehour and then at 150° C. for 5 hours to cure the material layer B.

100 parts by weight of a two-pack type silicone resin SCR1016Amanufactured by Shin-Etsu Chemical Co., Ltd. and 100 parts by weight ofa curing agent SCR1016B were mixed and defoamed by an agitationdefoaming apparatus AR-100 manufactured by Thinky Corporation. 2 μL ofthe obtained liquid mixture was injected to the semiconductor lightemitting device and maintained in a desiccator box which can beevacuated, for 5 minutes under conditions of 25° C. and 1 kPa, therebyto remove air bubbles included during the injection or dissolved air ormoisture. Thereafter, this semiconductor light emitting device wasmaintained under atmospheric pressure at 25° C. under a humidity of 50%to cure the above silicone resin layer, to form a material layer Dthereby to obtain a semiconductor light emitting device.

Examples III-5 Preparation of Semiconductor Light Emitting Device

Using a manually operated pipette, 0.5 μL of the above-mentionedfluoride complex phosphor-containing layer-forming liquid (1) wasdropped on a fluorine-coated heat resistant sheet and maintained in adroplet shape at 100° C. for one hour and then maintained at 150° C. for5 hours for curing thereby to form a material layer B.

A fluororesin (“EIGHT SEAL 3000” manufactured by Taihei Kasei Co., Ltd.)was dropped in an amount of 0.5 μL from above the material layer B andthen maintained and cured at 120° C. for 20 minutes. Then, the fluorinecoated heat resistant sheet contact side of the material layer B wasfaced upward, and 0.5 μL of the above fluororesin was dropped and curedin the same manner to form a material layer E around the material layerB.

100 parts by weight of a two-pack type silicone resin SCR1016Amanufactured by Shin-Etsu Chemical Co., Ltd. and 100 parts by weight ofa curing agent SCR1016B were mixed and defoamed by an agitationdefoaming apparatus AR-100 manufactured by Thinky Corporation. 1 μL ofthe obtained liquid mixture was injected to the semiconductor lightemitting device, then the material layer B coated by the above materiallayer E was put and further, 1 μL of the above liquid mixture wasinjected from above it and then maintained at 100° C. for one hour andthen at 150° C. for 5 hours thereby to obtain a semiconductor lightemitting device.

Examples III-6 Preparation of Semiconductor Light Emitting Device

100 parts by weight of a two-pack type silicone resin SCR1016Amanufactured by Shin-Etsu Chemical Co., Ltd. and 100 parts by weight ofa curing agent SCR1016B were mixed and defoamed by an agitationdefoaming apparatus AR-100 manufactured by Thinky Corporation. 1 μL ofthe obtained liquid mixture was injected to a light emitting devicehaving the above-mentioned light emitting device installed andmaintained in a desiccator box which can be evacuated, for 5 minutesunder conditions of 25° C. and 1 kPa, thereby to remove air bubblesincluded during the injection or dissolved air or moisture. Thereafter,this semiconductor light emitting device was maintained underatmospheric pressure at 25° C. under a humidity of 50% for 24 hours tocure the above silicone resin layer thereby to form a material layer C.

Then, using a manually operated pipette, 2 μL of the above-mentionedfluoride complex phosphor-containing layer-forming liquid (1) wasinjected to the light emitting device and maintained at 100° C. for onehour and then at 150° C. for 5 hours to cure the material layer B.

Further, on the material layer B, 1 μL of a liquid mixture of theabove-mentioned SCR1016A and SCR1016B was injected and maintained in adesiccator box which can be evacuated, for 5 minutes under conditions of25° C. and 1 kPa, to remove air bubbles included during the injection ordissolved air or moisture. Thereafter, this semiconductor light emittingdevice was maintained under atmospheric pressure at 25° C. under ahumidity of 50% to cure the above silicone resin layer to form thematerial layer D thereby to obtain a semiconductor light emittingdevice.

Comparative Example III-3 Preparation of Semiconductor Light EmittingDevice

Using a manually operated pipette, 4 μL of the above-mentioned fluoridecomplex phosphor-containing layer-forming liquid (1) was injected to thesemiconductor light emitting device and maintained in a desiccator boxwhich can be evacuated, for 5 minutes under conditions of 25° C. and 1kPa, to remove air bubbles included during the injection or dissolvedair or moisture. Thereafter, it was maintained at 100° C. for one hourand then at 150° C. for 5 hours to obtain a semiconductor light emittingdevice.

With respect to the light emitting devices obtained in Examples III-3 toIII-6 and Comparative Example III-3, the lighting test was carried outin the same manner as described above. The results are shown in Table26.

TABLE 26 RESULTS OF DURABILITY TESTS OF SEMICONDUCTOR LIGHT EMITTINGDEVICES OBTAINED IN EXAMPLES III-3 to III-6 AND COMPARATIVE EXAMPLEIII-3. Durability test results upon expiration of 200 hours Ex. III-3Ex. III-4 Ex. III-5 Ex. III-6 Comp. Ex. III-3 Not- Not- Not- Not- Not-Lighted lighted Lighted lighted Lighted lighted Lighted lighted Lightedlighted Measured Entire luminous 89% 92% 90% 84% 76% 95% 103%  97% 84%76% items flux (μW) Luminance (lm) 97% 97% 100%  92% 74% 95% 96% 93% 92%74% Cy 93% 97% 90% 89% 94% 99% 87% 92% 89% 94% Cx 99% 99% 97% 94% 97%99% 96% 97% 94% 97%

From the foregoing results, it is evident that the light emittingdevices having a material layer (material layer C to E) not containing afluoride complex phosphor are excellent in that when stored in anon-lighted state under conditions of a temperature of 85° C. and ahumidity of 85%, even upon expiration of 200 hours, the entire luminousflux and luminance maintaining rates are at least 80%, preferably atleast 85%, more preferably at least 90%. Further, it has been foundpossible that by improving the layer structure, also the durability atthe time of continuous lighting can be made to be at least 80%,preferably at least 85%, more preferably at least 90%.

INDUSTRIAL APPLICABILITY

According to the present invention, even with a LED backlight, it ispossible to accomplish a broad color reproducibility as the entire imageby adjustment with a color filter and at the same time, it is possibleto provide a color image display device whereby red, green and blueemissions are carried out by one chip without impairing the productivityon mounting, and yet, adjustment of the white balance is easy, and thus,its industrial applicability is very high in the fields of thecompositions for color filters, the color filters and the color imagedisplay devices.

In the foregoing, the present invention has been described withreference to specific embodiments, but it is apparent to those skilledin the art that various modifications are possible without departingfrom the concept and scope of the present invention.

The entire disclosures of Japanese Patent Application No. 2008-027506filed on Feb. 7, 2008 and Japanese Patent Application No. 2008-227990filed on Sep. 5, 2001 including specifications, claims, drawings andsummaries are incorporated herein by reference in their entireties.

1. A semiconductor light emitting device comprising a solid lightemitting device to emit light in a blue or deep blue region or in anultraviolet region and phosphors, in combination, wherein said phosphorscomprise a green emitting phosphor having at least one emission peak ina wavelength region of from 515 to 550 nm and a red emitting phosphorhaving at least one emission peak with a half-value width of at most 10nm in a wavelength region of from 610 to 650 nm; said red emittingphosphor has substantially no excitation spectrum in the emissionwavelength region of said green emitting phosphor and comprises Mn⁴⁺ asan activated element; and said green emitting phosphor and said redemitting phosphor have the variation rate of the emission peak intensityat 100° C. to the emission intensity at 25° C. of at most 40%, when thewavelength of the excitation light is 400 nm or 455 nm.
 2. Thesemiconductor light emitting device according to claim 1, wherein thegreen emitting phosphor comprises at least one compound selected fromthe group consisting of an aluminate phosphor, a sialon phosphor and anoxynitride phosphor.
 3. The semiconductor light emitting deviceaccording to claim 1, wherein the red emitting phosphor has thevariation rate of the emission peak intensity at 100° C. to the emissionpeak intensity at 25° C. of at most 18%, when the wavelength of theexcitation light is 455 nm.
 4. The semiconductor light emitting deviceaccording to claim 1, wherein the red emitting phosphor has a mainemission peak with a half-value width of at most 10 nm in a wavelengthregion of from 610 to 650 nm.
 5. The semiconductor light emitting deviceaccording to claim 1, wherein the red emitting phosphor is a fluoridecomplex phosphor, and said solid light emitting device is formed on anelectrically conductive substrate.
 6. The semiconductor light emittingdevice according to claim 5, wherein the red emitting phosphor has atleast 0.01 μg/min of thermally decomposed fluorine amount per 1 g of thephosphor at 200° C.
 7. The semiconductor light emitting device accordingto claim 6, wherein the red emitting phosphor has at 20° C. is at least0.005 g and at most 7 g of solubility in 100 g of water at 20° C.
 8. Thesemiconductor light emitting device according to claim 1, wherein thered emitting phosphor is a fluoride complex phosphor, and thesemiconductor light emitting device comprises a layer comprising saidred emitting phosphor and has at least one of the following structures(a) to (c): (a) a layer of a material not containing said red emittingphosphor between the solid light emitting device and the layercontaining said red emitting phosphor, (b) part or whole of the surfaceof the light emitting device covered by a layer of a material notcontaining said red emitting phosphor, and (c) the layer comprising saidred emitting phosphor, covered by a layer of a material not containingsaid red emitting phosphor.
 9. The semiconductor light emitting deviceaccording to claim 8, wherein the red emitting phosphor has at least0.01 μg/min of thermally decomposed fluorine amount per 1 g of thephosphor at 200° C.
 10. The semiconductor light emitting deviceaccording to claim 9, wherein the red emitting phosphor has at least0.005 g and at most 7 g of solubility in 100 g of water at 20° C. 11.The semiconductor light emitting device according to claim 1, whereinthe red emitting phosphor comprises a crystal phase having a chemicalcomposition represented by any one of the following formulae (1) to (8):M^(I) ₂[M^(IV) _(1-x)R_(x)F₆]  (1)M^(I) ₃[M^(III) _(1-x)R_(x)F₆]  (2)M^(II)[M^(IV) _(1-x)R_(x)F₆]  (3)M^(I) ₃[M^(IV) _(1-x)R_(x)F₇]  (4)M^(I) ₂[M^(III) _(1-x)R_(x)F₅]  (5)Zn₂[M^(III) _(1-x)R_(x)F₇]  (6)M^(I)[M^(III) _(2-2x)R_(2x)F₇]  (7)Ba_(0.65)Zr_(0.35)F_(2.70):Mn⁴⁺  (8) In the formulae (1) to (8), M^(I)is at least one monovalent group selected from the group consisting ofLi, Na, K, Rb, Cs and NH₄, M^(II) is an alkaline earth metal element,M^(III) is at least one metal element selected from the group consistingof Groups 3 and 13 of the Periodic Table, M^(IV) is at least one metalelement selected from the group consisting of Groups 4 and 14 of thePeriodic Table, R is an activated element comprising at least Mn, and xis a numerical value of 0<x<1.
 12. The semiconductor light emittingdevice according to claim 11, wherein the red emitting phosphorcomprises a crystal phase having a chemical composition represented bythe following formula (1′), wherein the proportion of Mn based on thetotal mols of M^(IV′) and Mn is at least 0.1 mol % and at most 40 mol %,and the specific surface area is at most 1.3 m²/g:M^(I′) ₂M^(IV′)F₆:R  (1′) In the formula (1′), M^(I′) is at least oneelement selected from the group consisting of K and Na, M^(IV′) is atleast one metal element selected from the group consisting of Groups 4and 14 of the Periodic Table comprising at least Si, and R is anactivated element comprising at least Mn.
 13. A backlight having thesemiconductor light emitting device according to claim 1 as a lightsource.
 14. A color image display device comprising light shutters, acolor filter having at least trichromatic color elements of red, greenand blue corresponding to the light shutters and the backlight asdefined in claim 13, in combination, wherein the relationship betweenthe light use efficiency Y and the NTSC ratio W representing the colorreproduction range of the color image display device is represented bythe following formula: $\begin{matrix}{Y \geqq {{{- 0.4}W} + {64\mspace{14mu} {W( {{{where}\mspace{14mu} W} \geqq 85} )}}}} & \; \\{X = \frac{\int_{380}^{780}{{\overset{\_}{x}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & {x = \frac{X}{X + Y + Z}} \\{Y = \frac{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & {y = \frac{Y}{X + Y + Z}} \\{Z = \frac{\int_{380}^{780}{{\overset{\_}{z}(\lambda)}{S(\lambda)}{T(\lambda)}\ {\lambda}}}{\int_{380}^{780}{{\overset{\_}{y}(\lambda)}{S(\lambda)}{\lambda}}}} & \;\end{matrix}$ wherein the definitions of the respective symbols are asfollows: x(λ), y(λ), z(λ): color matching functions of XYZ color systemS(λ): relative emission spectrum of the backlight T(λ): transmittance ofthe color filter
 15. The color image display device according to claim14, wherein the green pixel of the color filter comprises a zincphthalocyanine bromide pigment.
 16. The color image display deviceaccording to claim 14, wherein each pixel of the color filter has a filmthickness of at least 0.5 μm and at most 3.5 μm.
 17. A phosphorcomprising a crystal phase having a chemical composition represented bythe following formula (1′), wherein the proportion of Mn based on thetotal mols of M^(IV′) and Mn is at least 0.1 mol % and at most 40 mol %,and the specific surface area is at most 1.3 m²/g:M^(I′) ₂M^(IV′)F₆:R  (1′), wherein M^(I′) is at least one elementselected from the group consisting of K and Na, M^(IV′) is at least onemetal element selected from the group consisting of Groups 4 and 14 ofthe Periodic Table comprising at least Si, and R is an activated elementcomprising at least Mn.
 18. The phosphor according to claim 17, whereinthe particle size distribution of said red emitting phosphor has onepeak value.
 19. The phosphor according to claim 17, wherein the quantiledeviation of the particle size distribution is at most 0.6.
 20. Aprocess for producing the phosphor according to claim 17, comprisingreacting a solution comprising at least Si and F with a solutioncomprising at least K, Mn and F to obtain a compound represented by theformula (1′).
 21. A process for producing a phosphor comprising acrystal phase having a chemical composition represented by the followingformula (1′), comprising mixing at least two types of solutions eachcomprising at least one element selected from the group consisting of K,Na, Si, Mn and F:M^(I′) ₂M^(IV′)F₆:R  (1′), wherein M^(I′) is at least one elementselected from the group consisting of K and Na, M^(IV′) is at least onemetal element selected from the group consisting of Groups 4 and 14 ofthe Periodic Table comprising at least Si, and R is an activated elementcomprising at least Mn.
 22. A phosphor-containing composition comprisingthe phosphor according to claim 17 and a liquid medium.